Editing Rabbit (section)

==Biology==
[[File:Set of wax models showing development of the rabbit heart, twentieth century (24226156252).jpg|thumb|left|Wax models showing the development of the rabbit heart]]

===Evolution===
The earliest ancestor of rabbits and hares lived 55 million years ago in what is now [[Mongolia]].<ref>{{Cite journal|last1=Asher |first1=RJ |last2=Meng |first2=J |last3=Wible |first3=JR |last4=McKenna |first4=MC |last5=Rougier |first5=GW |last6=Dashzeveg |first6=D |last7=Novacek |first7=MJ |title=Stem Lagomorpha and the antiquity of Glires |journal=Science |date=February 18, 2005 |volume=307 |issue=5712 |pages=1091–4 |doi= 10.1126/science.1107808 |pmid= 15718468|bibcode=2005Sci...307.1091A }}</ref> Because the rabbit's [[epiglottis]] is engaged over the soft palate except when swallowing, the rabbit is an [[obligate nasal breathing|obligate nasal breather]].<ref>{{Cite journal|last1=Johnson-Delaney|first1= CA |last2=Orosz |first2=SE |title=Rabbit respiratory system: clinical anatomy, physiology and disease |journal=Vet Clin North Am Exot Anim Pract |date=May 2011 |volume=14 |issue=2 |pages=257–66 |doi= 10.1016/j.cvex.2011.03.002 |pmid= 21601814}}</ref> As lagomorphs, rabbits have two sets of [[incisor]] teeth, one behind the other, a manner in which they differ from rodents, which only have one set of incisors.{{sfn|Alves|Ferrand|Hackländer|2008|pages=1-9}} Another difference is that for rabbits, all of their teeth continue to grow, whereas for most rodents, only their incisors continue to grow.  [[Carl Linnaeus]] originally grouped rabbits and rodents under the class [[Glires]]; later, they were separated as the scientific consensus is that many of their similarities were a result of [[convergent evolution]]. DNA analysis and the discovery of a common ancestor have supported the view that they share a common lineage, so rabbits and rodents are now often grouped together in the clade or superorder Glires.<ref name="VellaDonnelly">{{Cite book|editor-first1=Katherine |editor-last1=Quesenberry |editor-first2=Connie J. |editor-last2=Orcutt |editor-first3=Christoph |editor-last3=Mans |editor-first4=James W. |editor-last4=Carpenter |title=Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery |edition=4th |date=2020 |chapter=Basic Anatomy, Physiology, and Husbandry of Rabbits |pages=131–149 |first1=Thomas M. |last1=Donnelly|first2= David |last2=Vella |doi=10.1016/B978-0-323-48435-0.00011-3 |isbn=978-0-323-48435-0 }}</ref><ref name="Kriegs">{{Cite journal |last1=Kriegs |first1=JO |last2=Churakov |first2=G|last3=Jurka |first3=J |last4=Brosius |first4=J |last5=Schmitz |first5=J |title=Evolutionary history of 7SL RNA-derived SINEs in Supraprimates |journal=Trends in Genetics |volume=23 |issue=4 |pages=158–61 |date=April 2007 |pmid=17307271 |doi=10.1016/j.tig.2007.02.002 }}</ref>

===Morphology===
[[File:Cmglee Horniman rabbit skin skeleton.jpg|thumb|left|Skeleton of the rabbit]]
Since speed and agility are a rabbit's main defenses against predators, rabbits have large hind leg bones and well-developed musculature. Though [[plantigrade]] at rest, rabbits are on their toes while running, assuming a more [[digitigrade]] posture.<ref>{{Cite journal |last1=Hall |first1=Patrick |last2=Stubbs |first2=Caleb |last3=Anderson |first3=David E. |last4=Greenacre |first4=Cheryl |last5=Crouch |first5=Dustin L. |date=2022-06-17 |title=Rabbit hindlimb kinematics and ground contact kinetics during the stance phase of gait |journal=PeerJ |language=en |volume=10 |pages=e13611 |doi=10.7717/peerj.13611 |doi-access=free |issn=2167-8359 |pmc=9208372 |pmid=35734635}}</ref> Rabbits use their strong claws for digging and (along with their teeth) for defense.<ref>{{cite journal |last1=d'Ovidio |first1=Dario |last2=Pierantoni |first2=Ludovica |last3=Noviello |first3=Emilio |last4=Pirrone |first4=Federica |title=Sex differences in human-directed social behavior in pet rabbits |journal=Journal of Veterinary Behavior |date=September 2016 |volume=15 |pages=37–42 |doi=10.1016/j.jveb.2016.08.072 }}</ref> Each front foot has four toes plus a [[dewclaw]]. Each hind foot has four toes (but no dewclaw).<ref name="van Praag">{{cite web |last1=van Praag |first1=Esther |year=2005 |title=Deformed claws in a rabbit, after traumatic fractures |url=http://www.medirabbit.com/EN/Bone_diseases/Anomalies/Nail_kas_en.pdf |publisher=MediRabbit }}</ref>

[[File:Wild black Oryctologus cuniculus.jpg|thumb|upright|[[Melanism|Melanistic]] coloring{{pb}}<small>''Oryctologus cuniculus''{{pb}}European rabbit (wild)</small>]]
Most wild rabbits (especially [[#Differences from hares|compared to hares]]) have relatively full, egg-shaped bodies. The soft coat of the wild rabbit is [[agouti (coloration)|agouti]] in coloration (or, rarely, [[melanism|melanistic]]), which aids in [[camouflage]]. The tail of the rabbit (with the exception of the [[Cottontail rabbit|cottontail species]]) is dark on top and white below. Cottontails have white on the top of their tails.<ref name="Encyclopædia Britannica">{{cite encyclopedia |title=rabbit |encyclopedia=[[Encyclopædia Britannica]] |publisher=[[Encyclopædia Britannica, Inc.]] |location=Chicago |edition=Standard |year=2007 }}</ref>

As a result of the position of the eyes in its skull and the size of the cornea, the rabbit has a panoramic field of vision that encompasses nearly 360 degrees.<ref>{{Citation |last1=Peiffer |first1=Robert L. |title=Models in Ophthalmology and Vision Research |date=1994 |journal=The Biology of the Laboratory Rabbit |pages=409–433 |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-469235-0.50025-7 |isbn=978-0-12-469235-0 |pmc=7149682 |last2=Pohm-Thorsen |first2=Laurie |last3=Corcoran |first3=Kelly}}</ref> However, there is a blind spot at the bridge of the nose, and because of this, rabbits cannot see what is below their mouth and rely on their lips and [[whiskers]] to determine what they are eating. Blinking occurs 2 to 4 times an hour.<ref name="VellaDonnelly" />

===Hind limb elements===
[[File:Rabbit hind limb skeleton.jpg|thumb|left|A specimen of the skeletal articulations of rabbit's hind limbs in the [[Pacific Lutheran University]] natural history collection]]
The anatomy of rabbits' hind limbs is structurally similar to that of other land mammals and contributes to their specialized form of locomotion. The bones of the hind limbs consist of long bones (the [[femur]], [[tibia]], [[fibula]], and [[phalanges]]) as well as short bones (the [[Navicular bone|tarsals]]). These bones are created through [[endochondral ossification]] during fetal development. Like most land mammals, the round head of the femur [[Articulation (anatomy)|articulates]] with the [[acetabulum]] of the [[os coxae]], the hip bone. The femur articulates with the tibia, but not the fibula, which is fused to the tibia. The tibia and fibula articulate with the tarsals of the [[Pes (anatomy)|pes]], commonly called the foot. The hind limbs of the rabbit are longer than the front limbs. This allows them to produce their hopping form of locomotion. Longer hind limbs are more capable of producing faster speeds. Hares, which have longer legs than [[cottontail rabbit]]s, are able to move considerably faster.<ref>{{Cite book|url=https://archive.org/details/practicalanatom00bensgoog|page=[https://archive.org/details/practicalanatom00bensgoog/page/n5 1]|quote=rabbit skeletal anatomy.|title=Practical anatomy of the rabbit|last=Bensley|first=Benjamin Arthur|date=1910|publisher=The University Press}}</ref> The hind feet have four long toes that allow for digitigrade movement, which are webbed to prevent them from spreading when hopping.<ref>{{Cite news|url=https://www.merckvetmanual.com/all-other-pets/rabbits/description-and-physical-characteristics-of-rabbits#v34404688|title=Description and Physical Characteristics of Rabbits – All Other Pets – Merck Veterinary Manual|work=Merck Veterinary Manual|access-date=2018-05-11}}</ref> Rabbits do not have paw pads on their feet like most other animals that use digitigrade locomotion. Instead, they have coarse compressed hair that offers protection.<ref>{{cite web|url=http://www.exoticpetvet.net/smanimal/rabanatomy.html|title=Rabbit Anatomy|last=D.A.B.V.P.|first=Margaret A. Wissman, D.V.M.|website=exoticpetvet.net|access-date=2018-05-11}}</ref>

====Musculature====
[[File:Lateral view of rabbit hind limb.jpg|thumb|The rabbit's hind limb (lateral view) includes muscles involved in the quadriceps and hamstrings.]]

Rabbits have muscled hind legs that allow for maximum force, maneuverability, and acceleration that is divided into three main parts: foot, thigh, and leg. The hind limbs of a rabbit are an exaggerated feature. They are much longer and can provide more force than the forelimbs,<ref name=":6" /> which are structured like brakes to take the brunt of the landing after a leap.<ref name=":7">{{Citation |last1=Khan |first1=Madiha |title=Lagomorpha Locomotion |date=2021 |encyclopedia=Encyclopedia of Animal Cognition and Behavior |pages=1–6 |editor-last=Vonk |editor-first=Jennifer |url=http://link.springer.com/10.1007/978-3-319-47829-6_1199-1 |access-date=2024-10-08 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-47829-6_1199-1 |isbn=978-3-319-47829-6 |last2=Suh |first2=Angela |last3=Lee |first3=Jenny |last4=Granatosky |first4=Michael C. |editor2-last=Shackelford |editor2-first=Todd|url-access=subscription }}</ref> The force put out by the hind limbs is contributed by both the structural anatomy of the fusion of the tibia and fibula, and by the muscular features.<ref name=":6">{{Cite book |last1=Lumpkin |first1=Susan |last2=Seidensticker |first2=John |date=2011 |title=Rabbits: the animal answer guide |publisher=Johns Hopkins University Press |isbn=978-1-4214-0126-3|location=Baltimore|oclc=794700391}}</ref>

Bone formation and removal, from a cellular standpoint, is directly correlated to hind limb muscles. Action pressure from muscles creates force that is then distributed through the skeletal structures. Rabbits that generate less force, putting less stress on bones are more prone to osteoporosis due to bone [[rarefaction]].<ref>{{cite journal |last1=Geiser |first1=Max |last2=Trueta |first2=Joseph |title=Muscle action, bone rarefaction and bone formation |journal=The Journal of Bone and Joint Surgery. British Volume |date=May 1958 |volume=40-B |issue=2 |pages=282–311 |doi=10.1302/0301-620X.40B2.282 |pmid=13539115 |doi-access=free }}</ref> In rabbits, the more fibers in a muscle, the more resistant to fatigue. For example, [[hare]]s have a greater resistance to fatigue than [[Cottontail rabbit|cottontails]]. The muscles of rabbit's hind limbs can be classified into four main categories: [[hamstring]]s, [[Quadriceps femoris muscle|quadriceps]], [[dorsiflexors]], or [[plantar flexors]]. The quadriceps muscles are in charge of force production when jumping. Complementing these muscles are the hamstrings, which aid in short bursts of action. These muscles play off of one another in the same way as the plantar flexors and dorsiflexors, contributing to the generation and actions associated with force.<ref>{{cite journal |last1=Lieber |first1=Richard L. |last2=Blevins |first2=Field T. |title=Skeletal muscle architecture of the rabbit hindlimb: Functional implications of muscle design |journal=Journal of Morphology |date=January 1989 |volume=199 |issue=1 |pages=93–101 |doi=10.1002/jmor.1051990108 |pmid=2921772 |s2cid=25344889 }}</ref>

===Ears===
[[File:Anatomy and physiology of animals The ear.jpg|thumb|Anatomy of mammalian ear]]
[[File:Holland Lop Ears UpDown.png|thumb|A [[Holland Lop]] resting with one ear up and one ear down. Some rabbits can adjust their ears to hear distant sounds.]]
Within the order of [[Lagomorpha|lagomorphs]], the ears are used to detect and avoid predators.{{sfn|Varga|2013|page=62}} In the family [[Leporidae]], the ears are typically longer than they are wide, and are in general relatively long compared to other mammals.<ref name="CapeHare" /><ref>{{Citation |last1=Bertolino |first1=Sandro |title=Eastern Cottontail Sylvilagus floridanus (J. A. Allen, 1890) |date=2023 |work=Primates and Lagomorpha |pages=67–78 |editor-last=Hackländer |editor-first=Klaus |url=https://link.springer.com/referenceworkentry/10.1007/978-3-030-34043-8_14 |access-date=2024-09-16 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-34043-8_14 |isbn=978-3-030-34042-1 |last2=Brown |first2=David E. |last3=Cerri |first3=Jacopo |last4=Koprowski |first4=John L. |editor2-last=Alves |editor2-first=Paulo C.|url-access=subscription }}</ref>

According to [[Allen's rule]], [[endotherm]]ic animals adapted to colder climates have shorter, thicker limbs and appendages than those of similar animals adapted to warm climates. The rule was originally derived by comparing the ear lengths of ''Lepus'' species across the various climates of North America.<ref>{{cite journal |first=Joel Asaph |last=Allen |authorlink=Joel Asaph Allen |title=The influence of Physical conditions in the genesis of species |journal=Radical Review |year=1877 |volume=1 |pages=108–140 |url=http://people.wku.edu/charles.smith/biogeog/ALLE1877.htm}}</ref> Subsequent studies show that this rule remains true in the Leporidae for the ears specifically,<ref>{{Cite journal |last=Stevenson |first=Robert D. |date=1986 |title=Allen's Rule in North American Rabbits (Sylvilagus) and Hares (Lepus) Is an Exception, Not a Rule |url=https://www.jstor.org/stable/1380884 |journal=Journal of Mammalogy |volume=67 |issue=2 |pages=312–316 |doi=10.2307/1380884 |jstor=1380884 |issn=0022-2372|url-access=subscription }}</ref> in that the surface area of rabbits' and hares' ears are enlarged in warm climates;<ref>{{Cite web |url=https://fieldguide.mt.gov/speciesDetail.aspx?elcode=AMAEB03050 |work=Montana Field Guide |publisher=Montana Natural Heritage Program and Montana Fish, Wildlife and Parks |title=Black-tailed Jackrabbit - Lepus californicus |access-date=24 September 2024}}</ref> the ears are an important structure to aid [[thermoregulation]]<ref name=":1">{{Cite journal|doi=10.1016/0024-3205(71)90161-5 |title=The rabbit ear as a temperature sensor |first1=Matthew J. |last1=Kluger |first2=Richard R. |last2=Gonzalez |first3=John W. |last3=Mitchell |first4=James D. |last4=Hardy |journal=Life Sciences |volume=10 |issue= 15 |date=1 August 1971 |pages= 895–899|pmid=5566134 }}</ref> as well as in detecting predators due to the way the outer, middle, and inner ear muscles coordinate with one another. The ear muscles also aid in maintaining balance and movement when fleeing predators.<ref>{{Cite journal|last=Meyer|first=D. L.|date=1971|title=Single Unit Responses of Rabbit Ear-Muscles to Postural and Accelerative Stimulation|journal=Experimental Brain Research|volume=14|issue=2|pages=118–26|doi=10.1007/BF00234795|pmid=5016586|s2cid=6466476}}</ref>

The [[auricle (anatomy)|auricle]], also known as the pinna, is a rabbit's outer ear.<ref name="Capello 2006">{{Cite journal|last=Capello|first=Vittorio|date=2006|title=Lateral Ear Canal Resection and Ablation in Pet Rabbits|url=http://www.ivis.org/proceedings/navc/2006/SAE/617.pdf?LA=1|journal=The North American Veterinary Conference|volume=20|pages=1711–1713}}</ref> The rabbit's pinnae represent a fair part of the body surface area. It is theorized that the ears aid in dispersion of heat at temperatures above {{convert|30|C|F|abbr=on }}, with rabbits in warmer climates having longer pinnae due to this. Another theory is that the ears function as shock absorbers that could aid and stabilize rabbits' vision when fleeing predators, but this has typically only been seen in hares.<ref name="VellaDonnelly" /> The rest of the outer ear has bent canals that lead to the [[eardrum]] or [[Eardrum|tympanic membrane]].<ref name="Parsons 2018">{{Cite journal|last=Parsons|first=Paige K.|date=2018|title=Rabbit Ears: A Structural Look: ...injury or disease, can send your rabbit into a spin|url=https://rabbit.org/journal/4-11/ear.html|journal=House Rabbit Society}}</ref>

The middle ear, separated by the outer eardrum in the back of the rabbit's skull, contains three bones: the hammer, anvil, and stirrup, collectively called [[ossicles]], which act to decrease sound before it hits the inner ear; in general, the ossicles act as a barrier to the inner ear for sound energy.<ref name="Parsons 2018" />

Inner ear fluid, called [[endolymph]], receives the sound energy. After receiving the energy. The inner ear comprises two parts: the [[cochlea]] that uses sound waves from the ossicles, and the [[vestibular apparatus]] that manages the rabbit's position in regard to movement. Within the cochlea a [[basilar membrane]] contains sensory hair structures that send nerve signals to the brain, allowing it to recognize different sound frequencies. Within the vestibular apparatus three semicircular canals help detect [[angular motion]].<ref name="Parsons 2018" />

==== Thermoregulation ====
[[File:California High Desert Cottontail Resting (cropped).jpg|thumb|The blood flow through the rabbit's ears help with thermoregulation, as seen in this [[desert cottontail]].<ref>{{Cite journal|doi=10.2307/1378969 |journal=Journal of Mammalogy |date=31 August 1973 |volume=54 |issue=3 |title=Acclimatization of Thermoregulation in the Desert Cottontail, Sylvilagus audubonii |last=Hinds |first=David S. |pages=708–728|jstor=1378969 |pmid=4744934 }}</ref>]]
The pinnae, which contain a vascular network and arteriovenous shunts, aid in thermoregulation.<ref name="VellaDonnelly" /> In a rabbit, the optimal body temperature is around {{convert|38.5|-|40.0|C|F|abbr=on }}.<ref>{{cite book |last1=Fayez |first1=I |title=Rabbit production in hot climates |last2=Marai |first2=M |last3=Alnaimy |first3=A |last4=Habeeb |first4=M |publisher=CIHEAM |year=1994 |editor1-last=Baselga |editor1-first=M |location=Zaragoza |pages=33–41 |chapter=Thermoregulation in rabbits |editor2-last=Marai |editor2-first=I.F.M. |chapter-url=http://om.ciheam.org/article.php?IDPDF=95605277}}</ref> If their body temperature exceeds or does not meet this optimal temperature, the rabbit must make efforts to return to [[homeostasis]]. Homeostasis of body temperature is maintained by changing the amount of blood flow that passes through the highly vascularized ears,<ref name=":1" />{{Sfn|Varga|2013|p=12}} as rabbits have few to no [[sweat gland]]s.<ref>{{Cite journal |last1=Oladimeji |first1=Abioja Monsuru |last2=Johnson |first2=Temitope Gloria |last3=Metwally |first3=Khaled |last4=Farghly |first4=Mohamed |last5=Mahrose |first5=Khalid Mohamed |date=January 2022 |title=Environmental heat stress in rabbits: implications and ameliorations |url=https://link.springer.com/10.1007/s00484-021-02191-0 |journal=International Journal of Biometeorology |language=en |volume=66 |issue=1 |pages=1–11 |doi=10.1007/s00484-021-02191-0 |pmid=34518931 |issn=0020-7128|url-access=subscription }}</ref> Rabbits may also regulate their temperature by resting in depressions in the ground, known as forms.<ref>{{Cite journal |last1=Milling |first1=Charlotte R |last2=Rachlow |first2=Janet L |last3=Johnson |first3=Timothy R |last4=Forbey |first4=Jennifer S |last5=Shipley |first5=Lisa A |date=2017-09-01 |title=Seasonal variation in behavioral thermoregulation and predator avoidance in a small mammal |url=http://academic.oup.com/beheco/article/28/5/1236/3861738/Seasonal-variation-in-behavioral-thermoregulation |journal=Behavioral Ecology |language=en |volume=28 |issue=5 |pages=1236–1247 |doi=10.1093/beheco/arx084 |issn=1045-2249}}</ref>

===Respiratory system===
[[File:Dissected Rabbit Lungs.jpg|thumb|upright|Ventral view of dissected rabbit lungs with key structures labeled]]

The rabbit's nasal cavity lies dorsal to the oral cavity, and the two compartments are separated by the hard and soft palate.<ref name="Johnson-Delaney 2011" /> The nasal cavity itself is separated into a left and right side by a cartilage barrier, and it is covered in fine hairs that trap dust before it can enter the [[respiratory tract]].<ref name="Johnson-Delaney 2011" />{{sfn|Smith|Schenk|2019|page=73}} As the rabbit breathes, air flows in through the nostrils along the alar folds. From there, the air moves into the nasal cavity, also known as the [[Pharynx|nasopharynx]], down through the trachea, through the [[larynx]], and into the lungs.{{sfn|Smith|Schenk|2019|page=76}}<ref name="Jekl 2012">{{Cite journal|last=Jekl|first=Vladimi|date=2012|title=Approach to Rabbit Respiratory Disease|url=https://www.vin.com/apputil/content/defaultadv1.aspx?id=5328323&pid=11349&print=1|journal=WSAVA/FECAVA/BSAVA World Congress|quote=As obligate nasal breathers, rabbits with upper airway disease will attempt to breathe through their mouths, which prevents feeding and drinking and could be quickly fatal.}}</ref> The larynx functions as the rabbit's voice box, which enables it to produce a wide variety of sounds.{{sfn|Smith|Schenk|2019|page=73}} The trachea is a long tube embedded with cartilaginous rings that prevent the tube from collapsing as air moves in and out of the lungs. The trachea then splits into a left and right bronchus, which meet the lungs at a structure called the [[Root of the lung|hilum]]. From there, the bronchi split into progressively more narrow and numerous branches. The bronchi branch into bronchioles, into respiratory bronchioles, and ultimately terminate at the alveolar ducts. The branching that is typically found in rabbit lungs is a clear example of monopodial branching, in which smaller branches divide out laterally from a larger central branch.<ref name="Autifi 2015" />

The structure of the rabbit's nasal and oral cavities necessitates breathing through the nose. This is due to the fact that the epiglottis is fixed to the backmost portion of the soft palate.<ref name="Jekl 2012" /> Within the oral cavity, a layer of tissue sits over the opening of the glottis, which blocks airflow from the oral cavity to the trachea.<ref name="Johnson-Delaney 2011">{{Cite journal|last1=Johnson-Delaney|first1=Cathy A.|last2=Orosz|first2=Susan E.|year=2011|title=Rabbit Respiratory System: Clinical Anatomy, Physiology and Disease|journal=Veterinary Clinics of North America: Exotic Animal Practice|language=en|volume=14|issue=2|pages=257–266|doi=10.1016/j.cvex.2011.03.002|pmid=21601814}}</ref> The epiglottis functions to prevent the rabbit from aspirating on its food. Further, the presence of a soft and hard palate allow the rabbit to breathe through its nose while it feeds.{{sfn|Smith|Schenk|2019|page=76}}

[[File:Monopodial branching in Rabbit Lungs.jpg|thumb|Monopodial branching as seen in dissected rabbit lungs]]

Rabbits' lungs are divided into four lobes: the cranial, middle, caudal, and accessory lobes. The right lung is made up of all four lobes, while the left lung only has two: the cranial and caudal lobes.<ref name="Autifi 2015">{{Cite journal|last1=Autifi|first1=Mohamed Abdul Haye|last2=El-Banna|first2=Ahmed Kamal|last3=Ebaid|first3=Ashraf El- Sayed|date=2015|title=Morphological Study of Rabbit Lung, Bronchial Tree, and Pulmonary Vessels Using Corrosion Cast Technique|url=https://www.researchgate.net/publication/326010899|journal=Al-Azhar Assiut Medical Journal|volume=13|issue=3|pages=41–51}}</ref> To provide space for the heart, the left cranial lobe of the lungs is significantly smaller than that of the right.<ref name="Johnson-Delaney 2011" /> The diaphragm is a muscular structure that lies caudal to the lungs and contracts to facilitate respiration.<ref name="Johnson-Delaney 2011" /><ref name="Jekl 2012" />{{Anchor|title=Diet and eating habits|reason="Diet and eating habits" is the old section name, which was changed to "Digestion" on 24 February 2018 and then "Diet and digestion" on 8 July 2024}}

===Diet and digestion===
{{Main|Cecotrope}}

Rabbits are strict [[herbivore]]s<ref name=":9" /><ref name=":10" /> and are suited to a diet high in fiber, mostly in the form of [[cellulose]]. They will typically [[grazing (behaviour)|graze]] grass upon waking up and emerging from a burrow, and will move on to consume vegetation and other plants throughout the waking period; rabbits have been known to eat a wide variety of plants, including tree leaves and fruits, though consumption of fruit and lower fiber foods is common for pet rabbits where natural vegetation is scarce.{{sfn|Varga|2013|pages=13-33}}

Easily digestible food is processed in the [[gastrointestinal tract]] and expelled as regular feces. To get nutrients out of hard to digest fiber, rabbits ferment fiber in the cecum (part of the gastrointestinal tract) and then expel the contents as [[cecotrope]]s, which are reingested (cecotrophy or refection). The cecotropes are then absorbed in the small intestine to use the nutrients.<ref>{{Cite book|editor-first1=Katherine |editor-last1=Quesenberry |editor-first2=Connie J. |editor-last2=Orcutt |editor-first3=Christoph |editor-last3=Mans |editor-first4=James W. |editor-last4=Carpenter |first1=Susan M. |last1=Smith |title=Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery |edition=4th |date=2020 |chapter=Gastrointestinal Physiology and Nutrition of Rabbits |doi=10.1016/B978-0-323-48435-0.00013-7 |pages=162–173|isbn=978-0-323-48435-0 }}</ref> Soft cecotropes are usually consumed during periods of rest in underground burrows.{{sfn|Varga|2013|pages=13-33}}

[[File:Male rabbit genitalia.pdf|thumb|left|Dissected image of the male rabbit reproductive system with key structures labeled]]
Rabbits cannot vomit;<ref>{{cite book|url=https://books.google.com/books?id=bqz9-IUUwdcC&pg=PA359|page=359|title=The Experimental Animal in Biomedical Research: Care, Husbandry, and Well-Being-An Overview by Species, Volume 2|author=Bernard E. Rollin|publisher=CRC Press|date= 13 Mar 1995|isbn=978-0-8493-4982-9}}</ref> and therefore if buildup occurs within the intestines (due often to a diet with insufficient fibre),<ref>{{cite web|url=http://articles.extension.org/pages/61402/the-digestive-system-of-the-rabbit|title=The Digestive System of the Rabbit|last=Karr-Lilienthal, Phd (University of Nebraska – Lincoln)|first=Lisa|date=4 November 2011|website=eXtension (a Part of the Cooperative Extension Service)|archive-url=https://web.archive.org/web/20180106120117/http://articles.extension.org/pages/61402/the-digestive-system-of-the-rabbit|archive-date=6 January 2018|url-status=live|access-date=5 January 2018|df=dmy-all}}</ref> intestinal blockage can occur.<ref>{{cite web |title=Living with a House Rabbit |url=http://rabbitsinthehouse.org/?page_id=60 |access-date=21 September 2017 |url-status=live |archive-url=https://web.archive.org/web/20170921095830/http://rabbitsinthehouse.org/?page_id=60 |archive-date=21 September 2017 |df=dmy-all }}</ref>

===Reproduction===
[[File:Male rabbit reproduction system.png|thumb|Diagram of the male rabbit reproductive system with main components labeled]]
The adult male reproductive system forms the same as most mammals with the seminiferous tubular compartment containing the [[Sertoli cell]]s and an adluminal compartment that contains the [[Leydig cell]]s.<ref name="Foote 2000">{{Cite journal|last1=Foote|first1=Robert H|last2=Carney|first2=Edward W|year=2000|title=The rabbit as a model for reproductive and developmental toxicity studies|journal=Reproductive Toxicology|volume=14|issue=6|pages=477–493|doi=10.1016/s0890-6238(00)00101-5|pmid=11099874|bibcode=2000RepTx..14..477F |issn=0890-6238}}</ref> The Leydig cells produce [[testosterone]], which maintains libido<ref name="Foote 2000" /> and creates secondary sex characteristics such as the [[genital tubercle]] and [[penis]]. The Sertoli cells triggers the production of [[Anti-Müllerian hormone|Anti-Müllerian duct hormone]], which absorbs the Müllerian duct. In an adult male rabbit, the [[Penile sheath|sheath of the penis]] is cylinder-like and can be extruded as early as two months of age.<ref name="LafeberVet repro basics">{{cite web|last=Pollock |first=C.|url=https://lafeber.com/vet/rabbit-reproduction-basics/|title=Rabbit Reproduction Basics|date=2014-05-05|website=LafeberVet|language=en-US|access-date=2024-09-18}}</ref> The scrotal sacs lay lateral to the penis and contain [[Epididymis|epididymal]] fat pads which protect the testes. Between 10 and 14 weeks, the testes descend and are able to retract into the pelvic cavity to thermoregulate.<ref name="LafeberVet repro basics" /> Furthermore, the secondary sex characteristics, such as the testes, are complex and secrete many compounds. These compounds include [[fructose]], [[citric acid]], minerals, and a uniquely high amount of [[catalase]],<ref name="Foote 2000" /> all of which affect the characteristics of rabbit semen; for instance, citric acid is positively correlated with [[Agglutination (biology)|agglutination]],<ref>{{Cite journal |last1=Holtz |first1=W. |last2=Foote |first2=R. H. |date=1978-03-01 |title=Composition of Rabbit Semen and the Origin of Several Constituents |url=https://academic.oup.com/biolreprod/article/2767506/Composition |journal=Biology of Reproduction |language=en |volume=18 |issue=2 |pages=286–292 |doi=10.1095/biolreprod18.2.286 |pmid=630026 |issn=0006-3363}}</ref> and high amounts of catalase protect against premature [[capacitation]].<ref>{{Cite journal |last1=Foote |first1=Robert H. |last2=Hare |first2=Elizabeth |date=2000-09-10 |title=High Catalase Content of Rabbit Semen Appears to be Inherited |url=https://onlinelibrary.wiley.com/doi/10.1002/j.1939-4640.2000.tb02134.x |journal=Journal of Andrology |language=en |volume=21 |issue=5 |pages=664–668 |doi=10.1002/j.1939-4640.2000.tb02134.x |pmid=10975413 |issn=0196-3635}}</ref>

[[File:Female repro system labelled.JPG|thumb|Diagram of the female rabbit reproductive system with main components labeled]]
The adult female reproductive tract is [[Bipartite uterus|bipartite]], which prevents an embryo from translocating between uteri.<ref>{{Cite book|date=1974|title=The Biology of the Laboratory Rabbit|doi=10.1016/c2013-0-11681-9|isbn=978-0-12-742150-6|last1=Weisbroth|first1=Steven H.|last2=Flatt|first2=Ronald E.|last3=Kraus|first3=Alan L.}}</ref> The female [[urethra]] and vagina open into a [[urogenital sinus]] with a single [[urogenital opening]].<ref>{{Cite book |last1=Lukefahr |first1=Steven D. |url=https://books.google.com/books?id=uhBuEAAAQBAJ&dq=%22Urogenital+opening%22&pg=PA169 |title=Rabbit Production, 10th Edition |last2=McNitt |first2=James I. |last3=Cheeke |first3=Peter R. |last4=Patton |first4=Nephi M. |date=2022-04-29 |publisher=CABI |isbn=978-1-78924-978-1 |language=en}}</ref> The two uterine horns communicate to two cervixes and forms one [[vaginal canal]]. Along with being bipartite, the female rabbit does not go through an [[Estrous cycle|estrus cycle]], which causes mating [[induced ovulation (animals)|induced ovulation]].<ref name="LafeberVet repro basics" />

The average female rabbit becomes sexually mature at three to eight months of age and can conceive at any time of the year for the duration of her life. Egg and sperm production can begin to decline after three years,<ref name="Foote 2000" /> with some species such as those in genus ''Oryctolagus'' completely stopping reproduction at 6 years of age.{{sfn|Nowak|1999|page=1730}} During mating, the male rabbit will insert his penis into the female from behind, make rapid pelvic thrusts until [[ejaculation]], and throw himself backward off the female. [[Copulation (zoology)|Copulation]] lasts only 20–40 seconds.<ref>{{cite web|url=http://florida4h.org/projects/rabbits/MarketRabbits/Activity8_Mating4.html|title=Understanding the Mating Process for Breeding Rabbits|website=florida4h.org|access-date=2019-04-12}}</ref>

The rabbit [[gestation]] period is short and ranges from 27 to 30 days.<ref name=":9" /> A longer gestation period will generally yield a smaller litter while shorter gestation periods will give birth to a larger litter. The size of a single litter can range from 1 to 12 kits, depending on species.{{sfn|Nowak|1999|pages=1720-1732}} After birth, the only role of males is to protect the young from other rabbits, and the mother will leave the young in the nest most of the day, returning to nurse them once every 24 hours.<ref name=":9" /> The female can become pregnant again as early as the next day.<ref name="LafeberVet repro basics" />

After mating, the doe will begin to dig a burrow or prepare a nest before giving birth. Between three days and a few hours before giving birth another series of hormonal changes will cause her to prepare the nest structure. The doe will first gather grass for a structure, and an elevation in [[prolactin]] shortly before birth will cause her fur to shed that the doe will then use to line the nest, providing insulation for the newborn kits.<ref name="stress">{{cite journal |last1=Benedek |first1=I |last2=Altbӓcker |first2=V |last3=Molnár |first3=T |date=2021 |title=Stress reactivity near birth affects nest building timing and offspring number and survival in the European rabbit (''Oryctolagus cuniculus''). |journal=PLOS ONE |volume=16 |issue=1 |pages=e0246258 |bibcode=2021PLoSO..1646258B |doi=10.1371/journal.pone.0246258 |pmc=7845978 |pmid=33513198 |doi-access=free}}</ref>

The mortality rates of embryos are high in rabbits and can be due to infection, trauma, poor nutrition and environmental stress. A high fertility rate is necessary to counter this.<ref name="LafeberVet repro basics" /> More than half of rabbit pregnancies are aborted, causing embryos to be resorbed into the mother's body;{{sfn|Nowak|1999|page=1730}} vitamin deficiencies are a major cause of abortions in domestic rabbits.{{sfn|Varga|2013|pages=34-38}}

===Sleep===
{{Further|Sleep in animals}}

Rabbits may appear to be [[crepuscular]], but many species<ref name=":9" /> are naturally inclined towards [[nocturnal]] activity.<ref>{{cite journal |last1=Jilge |first1=B |year=1991 |title=The rabbit: a diurnal or a nocturnal animal? |journal=Journal of Experimental Animal Science |volume=34 |issue=5–6 |pages=170–183 |pmid=1814463 }}</ref> In 2011, the average sleep time of a rabbit in captivity was calculated at 8.4 hours per day;<ref>{{Cite journal|title=40 Winks? |first=Jennifer S. |last=Holland |journal=National Geographic |volume= 220 |issue=1 |date=July 2011}}</ref> previous studies have estimated sleep periods as long as 11.4 hours on average, undergoing both [[slow-wave sleep|slow-wave]] and [[rapid eye movement sleep]].<ref>{{Cite journal|doi=10.1016/S0163-1047(86)80016-4 |title=Sleep—wakefulness rhythms in the rabbit |first1=R.T. |last1=Pivik |first2=F.W. |last2=Bylsma |first3=P. |last3=Cooper |journal=Behavioral and Neural Biology |volume= 45| issue= 3 |date=May 1986 |pages= 275–286|pmid=3718392 }}</ref><ref>{{Cite journal|doi=10.1111/ejn.14265 |last1=Aguilar-Roblero |first1=R |last2=González-Mariscal |first2=G. |title=Behavioral, neuroendocrine and physiological indicators of the circadian biology of male and female rabbits |issue=1 |journal= Eur J Neurosci |date= 2020 |volume=51 |pages=429–453|pmid=30408249 }}</ref> Newborn rabbits will sleep for 22 hours a day before leaving the nest.{{sfn|Varga|2013|pages=84-85}} As with other [[prey animal]]s, rabbits often sleep with their eyes open, so that sudden movements will awaken the rabbit to respond to potential danger.<ref>{{cite web |url=https://rabbit.org/health/the-rabbit-eye-a-complete-guide |title=The Rabbit Eye: A Complete Guide |publisher= Rabbit.Org Foundation |first=Paige K. |last=Parsons |access-date=September 17, 2024}}</ref>

{{Anchor|Rabbit diseases|Diseases|Immunity|reason="Rabbit diseases" is the old section name, which was changed to "Diseases" on 24 February 2018}}

===Diseases and immunity===
{{see also|Rabbit health|:Category:Rabbit diseases}}

In addition to being at risk of disease from common pathogens such as ''[[Bordetella bronchiseptica]]'' and ''[[Escherichia coli]]'', rabbits can contract the virulent, species-specific viruses [[myxomatosis]],<ref name=":2" /> and a form of calicivirus which causes [[rabbit hemorrhagic disease]].<ref>{{cite book |url=http://www.publish.csiro.au/pid/6508.htm |title=Australia's War Against Rabbits |author1=Cooke, Brian Douglas |publisher=CSIRO Publishing |year=2014 |isbn=978-0-643-09612-7 |url-status=live |archive-url=https://web.archive.org/web/20140607140214/http://www.publish.csiro.au/pid/6508.htm |archive-date=7 June 2014 |df=dmy-all }}</ref> Myxomatosis is more hazardous to pet rabbits, as wild rabbits often have some immunity.<ref>{{multiref2|{{cite journal |last=Meredith |first=A |title=Viral skin diseases of the rabbit |journal=Veterinary Clinics of North America: Exotic Animal Practice |date=2013 |volume=16 |issue=3 |pages=705–714 |doi=10.1016/j.cvex.2013.05.010|pmid=24018033 |ref=none}}|{{cite journal |last=Kerr |first=P |title=Genomic and phenotypic characterization of myxoma virus from Great Britain reveals multiple evolutionary pathways distinct from those in Australia |journal=PLOS Pathogens |volume=13 |issue=3 |pages=e1006252 |date=2017|pmc=5349684 |pmid=28253375 |doi=10.1371/journal.ppat.1006252 |doi-access=free |ref=none}}}}</ref> Among the parasites that infect rabbits are tapeworms (such as ''[[Taenia serialis]])'', external parasites (including fleas and mites), [[coccidia]] species, ''[[Encephalitozoon cuniculi]]'',<ref name="nat lib cuniculi">{{cite journal|title=''Encephalitozoon cuniculi'' in pet rabbits: diagnosis and optimal management|last=Latney|first=La'Toya|journal= Veterinary Medicine: Research and Reports|date=2014 |volume=5 |pages=169–180 |doi=10.2147/VMRR.S49842 |doi-access=free |pmid=32670857 |pmc=7337189 }}</ref> and ''[[Toxoplasma gondii]]''.<ref>{{cite web |last=Wood |first=Maggie |title=Parasites of Rabbits |url=http://www.exoticpetvet.com/breeds/rabbitexpectations142.htm |work=Chicago Exotics, PC |access-date=8 April 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130302084348/http://www.exoticpetvet.com/breeds/rabbitexpectations142.htm |archive-date=2 March 2013 |df=dmy-all }}</ref><ref>{{cite web |last=Boschert |first=Ken |title=Internal Parasites of Rabbits |url=http://netvet.wustl.edu/species/rabbits/rabparas.txt |work=Net Vet |access-date=8 April 2013 |url-status=live |archive-url=https://web.archive.org/web/20130402055049/http://netvet.wustl.edu/species/rabbits/rabparas.txt |archive-date=2 April 2013 |df=dmy-all }}</ref> Domesticated rabbits with a diet lacking in high-fiber sources, such as hay and grass, are susceptible to potentially lethal gastrointestinal stasis.<ref>{{cite web |last=Krempels |first=Dana |title=GastroIntestinal Stasis, The Silent Killer |url=http://www.bio.miami.edu/hare/ileus.html |work=Department of Biology at the University of Miami |access-date=21 September 2017 |url-status=live |archive-url=https://web.archive.org/web/20170619101231/http://www.bio.miami.edu/hare/ileus.html |archive-date=19 June 2017 |df=dmy-all }}</ref> Rabbits and hares are almost never found to be infected with [[rabies]] and have not been known to transmit rabies to humans.<ref name="CDCRabies">{{cite web |title=Rabies: Other Wild Animals |url=https://www.cdc.gov/rabies/exposure/animals/other.html |publisher=Centers for Disease Control and Prevention |access-date=20 December 2012 |date=15 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20101220085305/http://www.cdc.gov/rabies/exposure/animals/other.html |archive-date=20 December 2010 |df=dmy-all }}</ref>

[[Rabbit hemorrhagic disease]] (RHD) is a highly infectious rabbit-specific disease caused by strains of [[Rabbit hemorrhagic disease|rabbit hemorrhagic disease virus]] (RHDV), including [[rabbit hemorrhagic disease virus type 2|type 2]] (RHDV2).<ref name="RHDV2">{{cite web | title=Rabbit hemorrhagic disease | website=[[American Veterinary Medical Association]] | url=https://www.avma.org/resources-tools/animal-health-and-welfare/animal-health/rabbit-hemorrhagic-disease | access-date=2022-08-07}}</ref> The disease was first described in domestic Angora rabbits imported from Germany to [[Jiangsu]], China in 1984, and quickly spread to Korea, Italy, and the rest of Europe. The disease spread to the Americas from 1988, first appearing in rabbits imported to Mexico, but subsequent outbreaks were infrequent, as RHDV only affected the European rabbit species.<ref>{{Cite journal |last1=Abrantes |first1=Joana |last2=van der Loo |first2=Wessel |last3=Le Pendu |first3=Jacques |last4=Esteves |first4=Pedro J. |date=2012-02-10 |title=Rabbit haemorrhagic disease (RHD) and rabbit haemorrhagic disease virus (RHDV): a review |journal=Veterinary Research |volume=43 |issue=1 |pages=12 |doi=10.1186/1297-9716-43-12 |doi-access=free |issn=1297-9716 |pmc=3331820 |pmid=22325049}}</ref> RHDV2, a strain of RHD-causing virus that affects both domestic and wild lagomorphs, such as hares, was detected for the first time in France in 2010.<ref>{{Cite journal |last1=Bárcena |first1=Juan |last2=Guerra |first2=Beatriz |last3=Angulo |first3=Iván |last4=González |first4=Julia |last5=Valcárcel |first5=Félix |last6=Mata |first6=Carlos P. |last7=Castón |first7=José R. |last8=Blanco |first8=Esther |last9=Alejo |first9=Alí |date=2015-09-24 |title=Comparative analysis of rabbit hemorrhagic disease virus (RHDV) and new RHDV2 virus antigenicity, using specific virus-like particles |journal=Veterinary Research |volume=46 |issue=1 |pages=106 |doi=10.1186/s13567-015-0245-5 |doi-access=free |issn=1297-9716 |pmc=4581117 |pmid=26403184}}</ref> RHDV2 has since spread to the rest of Europe, Canada,<ref>{{Cite journal |last1=Ambagala |first1=Aruna |last2=Schwantje |first2=Helen |last3=Laurendeau |first3=Sonja |last4=Snyman |first4=Heindrich |last5=Joseph |first5=Tomy |last6=Pickering |first6=Bradley |last7=Hooper-McGrevy |first7=Kathleen |last8=Babiuk |first8=Shawn |last9=Moffat |first9=Estella |last10=Lamboo |first10=Lindsey |last11=Lung |first11=Oliver |last12=Goolia |first12=Melissa |last13=Pinette |first13=Mathieu |last14=Embury-Hyatt |first14=Carissa |date=July 2021 |title=Incursions of rabbit haemorrhagic disease virus 2 in Canada—Clinical, molecular and epidemiological investigation |url=https://onlinelibrary.wiley.com/doi/10.1111/tbed.14128 |journal=Transboundary and Emerging Diseases |language=en |volume=68 |issue=4 |pages=1711–1720 |doi=10.1111/tbed.14128 |pmid=33915034 |issn=1865-1674|url-access=subscription }}</ref> Australia,<ref>{{Cite journal |last1=Ramsey |first1=David S. |last2=Patel |first2=Kandarp K. |last3=Campbell |first3=Susan |last4=Hall |first4=Robyn N. |last5=Taggart |first5=Patrick L. |last6=Strive |first6=Tanja |date=2023-05-12 |title=Sustained Impact of RHDV2 on Wild Rabbit Populations across Australia Eight Years after Its Initial Detection |journal=Viruses |language=en |volume=15 |issue=5 |pages=1159 |doi=10.3390/v15051159 |doi-access=free |issn=1999-4915 |pmc=10223972 |pmid=37243245}}</ref> and the United States.<ref name="washington-state">{{cite web | title=Deadly rabbit disease confirmed in Thurston County; vets urge vaccination | website=[[Washington State Department of Agriculture]] | date=2020-09-25 | url=https://agr.wa.gov/about-wsda/news-and-media-relations/news-releases?article=35585&culture=en-US | access-date=2022-08-07}}</ref><ref name="RHDV2" />