Kogiidae
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Kogiidae is a family comprising at least two extant species of Cetacea, the pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales. As their common names suggest, they somewhat resemble sperm whales, with squared heads and small lower jaws, but are much smaller, with much shorter skulls and more notable dorsal fins than sperm whales.<ref>Template:Cite book</ref> Kogiids are also characterized by a "false gill slit" behind their eyes.<ref>Template:Cite book</ref>
A number of extinct genera have been named.<ref name=":7">Template:Cite journal</ref>
TaxonomyEdit
There is some amount of uncertainty over if Kogiidae belongs in the sperm whale family. Research still suggests a close relationship between Kogiidae and sperm whales using mitochondrial DNA, which supports Kogiidae as part of the sperm whale family.<ref name=":2" /> This relationship is supported by similarities of the anatomical structures in the head, responsible for sound production, in particular the presence of a spermaceti organ.<ref>Template:Cite journal</ref> Other phylogenetic research raises further questions over a potential relationship between kogiids and Ziphiidae.<ref name=":2">Template:Cite journal</ref> Other questions exist regarding the high relatedness in mitochondrial DNA between Platanista and kogiids.<ref>Template:Cite journal</ref> Fossil evidence is limited for this family, which potentially limits an understanding of their relationship to other extant cetaceans.<ref name=":0" />
Researchers have proposed that K. sima may represent at least two genetically unique species, and further genetic research is needed to determine the real number of extant species of Kogiidae.<ref>Template:Cite journal</ref>
ORDER ARTIODACTYLA
- Infraorder Cetacea
- Parvorder Odontoceti toothed whales
- Superfamily Physeteroidea
- Family Kogiidae
- Genus Kogia<ref name=":3">Template:Cite journal</ref>
- Pygmy sperm whale, K. breviceps
- Dwarf sperm whale, K. sima
- Kogia pusilla †
- Kogia danomurai†
- Genus Aprixokogia †<ref name=":3" />
- Genus Kogiopsis†<ref name=":7"/>
- Genus Koristocetus†
- Genus Nanokogia†<ref name=":3" />
- Genus Pliokogia †<ref>Template:Cite journal</ref>
- Genus Praekogia†<ref name=":3" />
- Genus Scaphokogia†<ref name=":3" />
- Genus Thalassocetus†<ref name=":3" />
- Genus Kogia<ref name=":3">Template:Cite journal</ref>
- Family Kogiidae
- Superfamily Physeteroidea
- Parvorder Odontoceti toothed whales
BiologyEdit
Kogiid skulls are characterized by a very short rostrum, the smallest among extant cetaceans, as well as high levels of asymmetry, which is expected among odontocetes.<ref name=":0">Template:Cite book</ref><ref>Template:Cite journal</ref> Kogiid skulls have the most blunt mandible among extant cetaceans as well. Extant kogiidae also show relatively high encephalization quotient, the ratio between observed brain size and expected brain size. The pygmy sperm whale has an EQ of 1.78, while the dwarf sperm whale's EQ is 1.63.<ref name=":0" /> Kogiidae do possess spermaceti in their head like sperm whales.<ref>Template:Cite journal</ref> However, kogiid spermaceti is unique as the whales are able to control its temperature.<ref name=":4">Template:Cite journal</ref> Kogiidae are also homodonts, showing teeth all of the same size and shape.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Kogiidae possess a unique system of organs to produce sound, including a bagpipe-like structure to produce sound and an amplifying horn.<ref name=":4" />
Kogiidae have a modified colon which works as an "ink sac", storing liquid red feces.<ref name="Bloodworth 1–12">Template:Cite journal</ref> They are able to release over three gallons of this fecal "ink" to confuse or discourage predators.<ref name=":5">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
EcologyEdit
RangeEdit
Kogiidae are believed to be cosmopolitan species, inhabiting all oceans except polar waters, remaining between the 50° latitude lines.<ref name="Bloodworth 1–12"/>
Two fossilized species of Kogia sp. were shown to exhibit sympatry, similar to the two modern members of Kogia, which researchers suggested shows that this behavior has been part of Kogiidae for at least 3 million years.<ref>Template:Cite journal</ref>
Behavior and feedingEdit
Extant kogiids travel in small groups and rarely surface, potentially to avoid predators like orcas.<ref>Template:Cite journal</ref>
Kogiidae are deep diving whales, believed to dive up to depths of 500 m.<ref name=":0" /> Kogiids feed using a technique known as suction feeding, and their diet primarily consists of squid.<ref>Template:Cite journal</ref><ref name=":1">Template:Cite journal</ref> Pygmy sperm whales are able to eat larger prey than dwarf sperm whales, although their diet as a whole is relatively similar.<ref name=":1" /> They have also been observed using echolocation to find their prey, and their hearing places them in the "Very High Frequency" group of cetaceans that can hear well above 100 kHz.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Human threatsEdit
Most observations of Kogia have come from individuals tangled in fishing line or stranded individuals.<ref name=":0" /> There is a commercial fishery for K. breviceps in parts of southeast Asia and the Lesser Antilles.<ref name=":6">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Both species of extant Kogia have also been observed stranded with plastics blocking their intestines.<ref name=":5" /><ref name=":6" />