''Berthella ocellata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the family

Pleurobranchidae The Pleurobranchidae are a Taxonomy (biology), taxonomic family (biology), family of sea slugs, marine (ocean), marine gastropod molluscs in the clade Pleurobranchomorpha. Characteristics Species in the family Pleurobranchidae have a promine ...

. It is native to the eastern Atlantic Ocean and the Mediterranean Sea where it inhabits the shallow

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

Description

The adult length of ''Berthella ocellata'' is about . It has an oval shape when extended and moving around, and circular when stationary. The head bears a pair of small black eyes and the mouth is underneath, with the buccal veil protruding on either side. The

rhinophore A rhinophore is one of a pair of Chemoreceptor, chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, Marine (ocean), marine gastropod opisthobranch mollusks suc ...

s are just in front of the eyes, and are tubular, with a split on the under surface; they project from the front edge of the mantle. When moving, the foot trails behind the slug; the underside of the foot is whitish or pale brown. There are two distinct colour forms of this sea slug, either brown, or whitish; in both cases the body is covered with white or pink, translucent, slightly-domed tubercles, each surrounded by a white rim. The

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, 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 r ...

is yellow and

bipinnate The following terms are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade is divided into two or more leaflets ...

and is located between the mantle and the foot, on the right-hand side at the back. Under the mantle dorsally, there is a small, rudimentary, whitish internal shell.

Distribution and habitat

This species occurs in the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

, the eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

, including the

Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...

. It is found on rocks in the shallow

, mostly at depths less than but sometimes as deep as .

Ecology

Being

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

, ''B. ocellata'' spends the day under stones, in crevices or in caves; it feeds on sponges such as '' Plakina trilopha'', '' Plakinastrella copiosa'' and '' Corticium candelabrum'', using its muscular

radula The radula (; : radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters ...

to rasp off fragments. Its foot produces acidic secretions which are distasteful to

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

. These slugs are

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

s. The genital pores are on the right-hand side in front of the gill, and two individual slugs will position themselves in a head-to tail position, and each pass sperm to the other. Fertilisation is internal, and the eggs are probably laid in a gelatinous spiral, as is the case with other members of the genus.

References

* Ortea J. & Moro L. (2017). ''Redescripcion de ''Staurodoris atypica'' Eliot, 1906 y nuevas citas de "lesmas do mar" (Mollusca: Heterobranchia) para las islas de Cabo Verde.'' Avicennia. 20: 15–20.

External links

Delle Chiaje S. (1823-1831). Memorie sulla storia e notomia degli animali senza vertebre del regno di Napoli. Napoli: Fratelli Fernandes (vol. 1), and Società Tipografica (vol. 2-4). Vol. 1, pp. i-xii, 1-84 [1823
pp. 1-184 [1824]; vol. 2, pp. [1-4] + 185-224 [1825], pp. 225-444 [1826]; vol. 3, pp. i-xx, pp. 1-232 [1828]; vol. 4, pp. i-vii [1831], 1-116 [1830], pp. 117-214 [1831]; pl. 1–4; pl. 1-69 [date?], pl. 70-109 [1830) ] {{Taxonbar, from=Q13438945 Pleurobranchidae Molluscs of the Atlantic Ocean Molluscs of the Mediterranean Sea Gastropods described in 1830 Taxa named by Stefano delle Chiaje