Editing Sea turtle (section)

=== Symbiosis with barnacles ===
Sea turtles are believed to have a [[Commensalism|commensal]] relationship with some [[barnacle]]s, in which the barnacles benefit from growing on sea turtles without harming them. Barnacles are small, hard-shelled crustaceans found attached to multiple different substrates below or just above the ocean. The adult barnacle is a [[Sessility (zoology)|sessile]] organism; however, in its larval stage it is [[plankton]]ic and can move about the water column. The larval stage chooses where to settle and ultimately the habitat for its full adult life, which is typically between 5 and 10 years. However, estimates of age for a common sea turtle barnacle species, ''Chelonibia testudinaria'', suggest that this species lives for at least 21 months,<ref name=":15">{{Cite journal|last1=Doell|first1=Sophie A.|last2=Connolly|first2=Rod M.|last3=Limpus|first3=Colin J.|last4=Pearson|first4=Ryan M.|last5=van de Merwe|first5=Jason P.|date=2017|title=Using growth rates to estimate age of the sea turtle barnacle Chelonibia testudinaria|journal=Marine Biology|language=en|volume=164|issue=12|page=222|doi=10.1007/s00227-017-3251-5|bibcode=2017MarBi.164..222D |s2cid=31961046|issn=0025-3162}}</ref> with individuals older than this uncommon. ''Chelonibia'' barnacles have also been used to distinguish between the foraging areas of sea turtle hosts. By analyzing stable isotope ratios in barnacle shell material, scientist can identify differences in the water (temperature and salinity) that different hosts have been swimming through and thus differentiate between the home areas of host sea turtles.<ref>{{Cite journal|last1=Pearson|first1=Ryan M.|last2=van de Merwe|first2=Jason P.|last3=Gagan|first3=Michael K.|last4=Limpus|first4=Colin J.|last5=Connolly|first5=Rod M.|date=2019|title=Distinguishing between sea turtle foraging areas using stable isotopes from commensal barnacle shells|journal=Scientific Reports|language=en|volume=9|issue=1|pages=6565|doi=10.1038/s41598-019-42983-4|pmid=31024029|pmc=6483986|issn=2045-2322|bibcode=2019NatSR...9.6565P}}</ref>

A favorite settlement for barnacle larvae is the shell or skin around the neck of sea turtles. The larvae glue themselves to the chosen spot, a thin layer of flesh is wrapped around them and a shell is secreted. Many species of barnacles can settle on any substrate; however, some species of barnacles have an obligatory commensal relationship with specific animals, which makes finding a suitable location harder.<ref name="ZardusHadfield2004">{{Cite journal | last1 = Zardus | first1 = J. D. | last2 = Hadfield | first2 = M. G. | doi = 10.1651/C-2476 | title = Larval development and complemental males in ''Chelonibia testudinaria'', a barnacle commensal with sea turtles | journal = Journal of Crustacean Biology | volume = 24 | issue = 3 | pages = 409–421 | year = 2004 | doi-access = free| bibcode = 2004JCBio..24..409H }}</ref> Around 29 species of "turtle barnacles" have been recorded. However, it is not solely on sea turtles that barnacles can be found; other organisms also serve as a barnacle's settlements. These organisms include mollusks, whales, decapod crustaceans, manatees and several other groups related to these species.<ref>Epibiont Research Cooperative. 2007. [http://www.seaturtle.org/documents/ERC-SP1.pdf A synopsis of the literature on the turtle barnacle (Cirripedia: Balanomorpha: Coronuloidea) 1758–2007]. Accessed 28 Nov 2012.</ref>

Sea turtle shells are an ideal habitat for adult barnacles for three reasons. Sea turtles tend to live long lives, greater than 70 years, so barnacles do not have to worry about host death. However, mortality in sea turtle barnacles is often driven by their host shedding the scutes on which the barnacle is attached, rather than the death of the sea turtle itself.<ref name=":15" /> Secondly, barnacles are [[suspension feeder]]s. Sea turtles spend most of their lives swimming and following ocean currents and as water runs along the back of the sea turtle's shell it passes over the barnacles, providing an almost constant water flow and influx of food particles. Lastly, the long distances and inter-ocean travel these sea turtles swim throughout their lifetime offers the perfect mechanism for dispersal of barnacle larvae. Allowing the barnacle species to distribute themselves throughout global waters is a high fitness advantage of this commensalism.<ref>[http://bio390parasitology.blogspot.ca/2012/03/free-ride-under-sea-barnacles-and.html A free ride under the sea: barnacles and baleen whales]. Themes of Parasitology. 2012. Web. 28 Nov 2012.</ref>

This relationship, however, is not truly commensal. While the barnacles are not directly [[Parasitism|parasitic]] to their hosts, they have negative effects to the sea turtles on which they choose to reside. The barnacles add extra weight and drag to the sea turtle, increasing the energy it needs for swimming and affecting its ability to capture prey, with the effect increasing with the quantity of barnacles affixed to its back.{{Citation needed|reason=The previous reference for this paragraph does not seem to support it? http://true-wildlife.blogspot.ca/2011/01/barnacle.html|date=January 2022}}