''Tritonicula hamnerorum'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of dendronotid nudibranch. It is a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Tritoniidae Tritoniidae is a taxonomic family of nudibranchs in the suborder Cladobranchia, shell-less marine gastropod molluscs.MolluscaBase (2018)Tritoniidae Lamarck, 1809.Accessed on 2021-01-01 This family includes some of the largest known nudibranchs, ...

. A number of Caribbean species of ''Tritonia'' were moved to a new genus ''Tritonicula'' in 2020 as a result of an integrative taxonomic study of the family Tritoniidae.

Distribution

''Tritonicula hamnerorum'' is found in the Caribbean area with its range extending from the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

Curaçao Curaçao ( ; ; pap, Kòrsou, ), officially the Country of Curaçao ( nl, Land Curaçao; pap, Pais Kòrsou), is a Lesser Antilles island country in the southern Caribbean Sea and the Dutch Caribbean region, about north of the Venezuela coast ...

and the

Cayman Islands The Cayman Islands () is a self-governing British Overseas Territory—the largest by population in the western Caribbean Sea. The territory comprises the three islands of Grand Cayman, Cayman Brac and Little Cayman, which are located to the ...

.Rudman, W.B., 2002 (January 20
''Tritonia hamnerorum'' Gosliner & Ghiselin, 1987.
nSea Slug Forum. Australian Museum, Sydney.MolluscaBase eds. (2021)
MolluscaBase. ''Tritonicula hamnerorum'' (Gosliner & Ghiselin, 1987).
Accessed through: World Register of Marine Species on 2021-01-05 The distribution of ''Tritonicula hamnerorum'' includes Florida, Mexico, Belize, Bahamas, Cayman Islands and Panama.

Description

The shape of the body is elongate and narrow. Rhinophores are long with branched tips. Rhinophoral sheaths are elevated with an irregular edge. Edge of the oral veil has relatively long appendages. Background colour is translucent gray with a series of irregular, longitudinal, thin white lines that run along the length of the dorsum. Its colour, pink or pale lavender, matches the colour of its host sea fan, ''Gorgonia ventalina''. There are about twenty thin white stripes running the length of the body. There are series of nine, sparsely

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

s or cerata down each side of the body. ''Tritonicula hamnerorum'' is up to long.Welch J. J. (2010). "The “Island Rule” and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLoS ONE'' 5(1): e8776. doi:10.1371/journal.pone.0008776.

Ecology

Habitat

Found in shallow water reef habitats with its host ''Gorgonia ventalina''. Minimum recorded depth is 2 m. Maximum recorded depth is 4 m.

Feeding habits

''Tritonicula hamnerorum'' seems to feed exclusively on '' Gorgonia ventalina'' and extensive searches failed to locate any individuals on other parts of the reef, on mangroves or in

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

beds. ''Gorgonia ventalina'' contains secondary metabolites including one, " julieannafuran", which is distasteful to predators. ''Tritonicula hamnerorum'' seems to be unaffected by this and sequesters the compound, accumulating it in its tissues. This in turn makes the nudibranch distasteful to predatory fish, such as the bluehead wrasse ('' Thalassoma bifasciatum''), which avoid consuming this species. This species reportedly feeds on the octocorals ''Gorgonia ventalina'' and '' Gorgonia flabellum''.

Life cycle

This nudibranch lays small clusters containing several hundred

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

capsules on branches of its

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

coral. The morphology of the veliger larvae that hatch from these eggs suggest that they are

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

ic. Juveniles feed on the soft tissue overlying the skeleton of the sea fan while adults feed on the polyps. Within its range, the distribution of ''Tritonicula hamnerorum'' is very patchy. Usually one or a few individuals are found on a single sea fan, but very occasionally, as happened in an outbreak in 1992, a large number of juveniles occur. On this occasion, 1,700 were found in a dense aggregation on one side of an area of sea fan measuring . Because these juveniles were all the same size, researchers hypothesized that they may not have become planktonic but may have remained on the host after hatching and fed on plankton, like their host, before undergoing

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

. It was found on gorgonian sea fans in dense aggregations also in Panama.

References

This article incorporates Creative Commons (CC-BY-4.0) text from the referenceGoodheart J. A., Ellingson R. A., Vital X. G., Galvão Filho H. C., McCarthy J. B., Medrano S. M., Bhave V. J., García-Méndez K., Jiménez L. M., López G. & Hoover C. A. (2016). "Identification guide to the heterobranch sea slugs (Mollusca: Gastropoda) from Bocas del Toro, Panama". ''Marine Biodiversity Records'' 9(1): 56. {{Taxonbar, from=Q7844363 Tritoniidae Gastropods described in 1987