Okenia rosacea - AbsoluteAstronomy.com

Okenia rosacea is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

of a sea slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

, specifically a dorid

Doridacea

Doridacea is a taxonomic grouping of dorid nudibranchs, shell-less marine gastropod mollusks. included in the clade Euctenidiacea of the clade Nudibranchia.- Taxonomy :*Superfamily Doridoidea**Family Dorididae**Family Actinocyclidae...

nudibranch

Nudibranch

A nudibranch is a member of what is now a taxonomic clade, and what was previously a suborder, of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms...

, a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

gastropod mollusc in the family Goniodorididae

Goniodorididae

Goniodorididae are a taxonomic family of sea slugs, specifically dorid nudibranchs, marine gastropod molluscs in the order Opisthobranchia.-Genera:Genera in the family Goniodorididae include:* Ancula Lovén, 1846* Goniodoris Forbes & Goodsir, 1939...

.

They can be found along the coast of western North America from Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

to Baja California

Baja California

Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

.

These pink sea slugs are characterized by numerous long papillae on their back, tapering into a round tip. These papillae are sometimes more or less white at their tips. This pink color is produced by the xanthophyll

Xanthophyll

Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...

ic pigment hopkinsiaxanthin, most likely obtained through feeding on a cheilostomatous

Cheilostomata

Cheilostomata, an order of Bryozoa in the class Gymnolaemata, are exclusively marine, colonial invertebrate animals. Cheilostome colonies are composed of calcium carbonate and grow on a variety of surfaces, including rocks, shells, seagrass and kelps. The colony shapes range from simple encrusting...

bryozoan Integripelta bilabiata.

The mantle, foot and the head are merged into one entity with a flattened profile. The oral tentacles are lacking. The 20 gills are situated around the anal papillae and are somewhat shorter.

The shape of the taenioglossan radula

Radula

The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...

is unique in this family, as the middle tooth is large and elongate, ending in a hook-like tip. The lateral teeth are small and are actually reduced to a rudimentary plate.

Further reading