''Elacatinus colini'', the Belize sponge

goby The Gobioidei are a suborder of percomorph fish. Many of these fishes are called gobies. It is by far the largest and most diverse order within the order Gobiiformes, and one of the most diverse groups of ray-finned fish in general. The subord ...

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

Belize Belize is a country on the north-eastern 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 maritime boundary with Honduras to the southeast. P ...

and

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. It is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Ocean at the Gulf of Fonseca, ...

Etymology

Its

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

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 g ...

'' 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 fluid, serous and muc ...

. 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 The fus ...

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

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. 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 Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

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 () 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. It has been documented in history since Columbus ...

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

, 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 A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

survived in higher numbers when fed wild-caught

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

as opposed to

Rotifers The rotifers (, from Latin 'wheel' and 'bearing'), sometimes 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 Harris ...

(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 or '' sea monkeys''. 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 cent ...

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

. 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 Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

, 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 The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

, pigmented eyes, and two visible

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

. 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 Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

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 on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

. 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 Taxa named by John Ernest Randall Taxa named by Phillip S. Lobel Fish described in 2009