''Spurilla neapolitana'', the Neapolitan spurilla, 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 ...

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary time ...

, an aeolid nudibranch, a marine gastropod

mollusk 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 e ...

in the

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

Aeolidiidae Aeolidiidae, a family of aeolid nudibranchs, are a family of sea slugs, shell-less marine gastropod molluscs.Bouchet, P. (2014)''Aeolidiidae'' Gray, 1827.Accessed through: World Register of Marine Species on 2014-10-24 Most, or perhaps all, mem ...

. It is native to the western Atlantic Ocean, the Caribbean Sea and the Mediterranean Sea. This species was first described as ''Eolis neapolitana'' by the Italian naturalist Stefano delle Chiaje in 1841. However, although some authorities quote the year as 1823, the species does not appear in the first volume of delle Chiaje's memoirs, which was published that year. The species was later reassigned to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

'' Spurilla''.

Distribution

''Spurilla neapolitana'' is found in shallow temperate waters in the Mediterranean Sea, the western Atlantic Ocean, the Caribbean Sea, the Gulf of Mexico and Baja California. Molecular studies have shown that this is a

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

consisting of at least three species. The type ''Spurilla neapolitana'' is found in the eastern Atlantic Ocean, from Cape Verde and the Azores to Portugal, and in the Mediterranean Sea. The western Atlantic population was denoted as ''Spurilla braziliana'' by MacFarland (1909) and the Pacific specimens may also be ''S. braziliana''.

Description

''Spurilla neapolitana'' is a large nudibranch, growing to a length of in the Mediterranean Sea. The

rhinophore A rhinophore is one of a pair of chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, marine gastropod opisthobranch mollusks such as the nudibranchs, sea ha ...

s (the pair of sensory structures on the dorsal surface of the head) are lamellate. The

cerata :''The tortrix moth genus ''Cerata'' is considered a junior synonym of ''Cydia. Cerata, singular ceras, are anatomical structures found externally in nudibranch sea slugs, especially in aeolid nudibranchs, marine opisthobranch gastropod mollusks ...

(outgrowths of the body) are also flattened and have opaque white tips. These tips are known as

cnidosac A cnidosac is an anatomical feature that is found in the group of sea slugs known as aeolid nudibranchs, a clade of marine opisthobranch gastropod molluscs. A cnidosac contains cnidocytes, stinging cells that are also known as cnidoblasts or n ...

s and are defensive structures armed with

cnidocyte A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...

s (stinging cells) garnered from sea anemones that the nudibranch has eaten. The general colour of this species is orange or pinkish, perhaps depending on what it has been eating, often with dark streaking where the tortuous

digestive gland The hepatopancreas, digestive gland or midgut gland is an organ of the digestive tract of arthropods and molluscs. It provides the functions which in mammals are provided separately by the liver and pancreas, including the production of digestive e ...

is visible through the translucent skin and the walls of the cerata. Some individuals have opaque patches of white on the body wall.

Habitat

Minimum recorded depth is 0 m. Maximum recorded depth is 3 m.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.

Feeding habits

''Spurilla neapolitana'' feeds on sea anemones. The cnidocytes pass unharmed through the gut of the nudibranch to the tip of the cerata where they are stored, to be used in the animal's defence. The nudibranch's tissues harbour live intracellular

zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''S ...

(photosynthetic single celled organisms), also derived from the sea anemone. It has been shown that the nudibranch's

faeces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...

contain live zooxanthellae, theoretically capable of reinfecting sea anemones, and this may be an important means by which the sea anemones acquire their zooxanthellae.

References

External links