''Elacatinus colini'', the Belize sponge

goby Goby is a common name for many species of small to medium sized ray-finned fish, normally with large heads and tapered bodies, which are found in marine, brackish and freshwater environments. Traditionally most of the species called gobies have b ...

, is a species of goby native to the Western Central Atlantic Ocean, near

Belize Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wate ...

and Honduras. Its specific name honours Patrick L. Colin, of the Coral Reef Research Foundation, Palau, who made a comparative study of the genus ''

Elacatinus ''Elacatinus'' is a genus of small marine gobies, often known collectively as the neon gobies. Although only one species, ''E. oceanops'', is technically the "neon goby," because of their similar appearance, other members of the genus are genera ...

'' for his doctoral thesis.

Appearance

''Elacatinus colini'' was originally thought to be a color variant of ''E. xanthiprora'' from Florida but was recently classified as its own species due to the presence of a bright white, not yellow, stripe along its body. ''E. colini'' are typically around 3 cm in length (3.2 cm SL for males, 3.4 cm SL for females), and can be easily identified by the white strip running from its anterior to posterior end. On the ''E. colini's'' head, the lateral stripe is relatively small – about the same width as its pupil. However, on its body, the lateral stripe widens to about the same width as its eye. ''E. colini'' typically have 8 dorsal spines, 10-12 dorsal soft rays, 1 anal spine, 10–11 anal soft rays, and 17-19 pectoral rays. They lack scales and are covered with a thick adherent

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

. The bodies of ''E. colini'' are bluish-greenish gray above their lateral stripe, with the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

part of their head, iris, and lips exhibiting a bright yellow color and the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

part of their body being white. Their fins are a translucent gray color.

Habitat

''Elacatinus colini'' live in marine systems in symbiotic relationships with various species of sponges, using them as shelter. They have been found to live in Carrie Bow Cay in Belize and

Utila Utila ''(Isla de Utila)'' is the smallest of Honduras' major Bay Islands, after Roatán and Guanaja, in a region that marks the south end of the Mesoamerican Barrier Reef System, the second-largest in the world. The eastern end of the island i ...

Island in Honduras. They live in shallow sponge, between deep but it is possible that they live deeper as well. ''E. colini'' inhabit tropical areas, 17ºN - 16ºN, 88ºW - 89ºW. According to Tassell, ''E. colini'' can occupy an area of about 11,184 km².

Population

''Elacatinus colini'' were seemingly abundant in their local environment of

and Honduras, however, there is little data or research on their population trends.

Diet

In a study performed by Majoris, Francisco, Atema and Buston,Majoris, John E., et al. "Reproduction, Early Development, and Larval Rearing Strategies for Two Sponge-Dwelling Neon Gobies, Elacatinus Lori and E. Colini."Aquaculture, vol. 483, 2018, pp. 286-295. Elsevier.com. it was shown that ''E. colini'' larvae survived in higher numbers when fed wild-caught

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

as opposed to

Rotifers The rotifers (, from the Latin , "wheel", and , "bearing"), commonly called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John H ...

(microscopic aquatic animals) and Artemia (a genus of aquatic crustaceans). The study also showed that the standard length of ''E. colini'' was higher when fed a diet of

as opposed to

Artemia ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia L ...

or rotifer. Researchers postulated this could be because larvae may not have developed the ability to digest Artemia and Rotifer, because Artemia could have changed water quality and thus affected the ability of the ''E. colini'' larvae to survive, or because the Artemia could have depleted the oxygen levels in the water and consequently lowered the survival rate of ''E. colini''. However, this last hypothesis is the least likely because the research tanks were well oxygenated.

Reproduction

In the study conducted by Majoris et al., it was shown that before

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

, the bodies of both male and female ''E. colini'' turn dark grey/black. Researchers also concluded that ''E. colini'' spawned within 3–44 days of being introduced to the study tanks, which was faster than ''Elacatinus lori''. ''E. colini'' spawned in relatively small clutches in comparison to ''E. lori'' and spawned every 7.8 ± 1.7 days. The study also showed that male ''E. colini'' incubated the eggs by fanning/mouthing the clutch until it hatched, and females were sometimes observed to consume the larvae after hatching. ''E. colini'' spawn regularly for a period of 12 months, and embryos hatch with a fully functional mouth, inflated swim bladder, pigmented eyes, and two visible

otoliths An otolith ( grc-gre, ὠτο-, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The sa ...

. After hatching, larvae tend to swim up to the surface of the water, as they are attracted to the light and feed on rotifers starting at around 12 hours after hatching.

Development

''Elacatinus colini'' are born with a fully functional mouth, inflated swim bladder, pigmented eyes, and two visible otoliths. After about 18–20 days post hatch (dph), fin folds are completely gone, and the pelvic and dorsal fins begin to form. At around 20–28 dph, the pelvic fin elongates but remains unfused. Pre-settled larvae have elongated snouts, partially fused pelvic fins, and exhibit the first

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

. Once the pelvic fins have completely transformed into the pelvic disc, they begin to settle (earliest settlement begins at around 28 dph) and use their pelvic disc to suction onto surfaces. Settlement happens between 28–54 dph. The stripe along the body of ''E. colini'' develops immediately, while the yellow pigment on the snout takes a few days to develop.

Conservation

There are no current observed threats to ''E. colini'', however, the degradation of sponge habitats could negatively impact the species. Monitoring of the species can prevent any threats from drastically impacting the ''E. colini'' population. Further research concerning threats to this species and population trends need to be performed. However, despite the species' small distribution, ''E. colini'' is currently categorized as a Least Concern species.

References

{{Taxonbar, from=Q5755257 colini Symbiosis Fish described in 2009