Crepidula onyx, common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 the onyx slippersnail or onyx slipper snail, 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 sea snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

 with gill

Gill

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s, 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 Calyptraeidae

Calyptraeidae

Calyptraeidae, common name the slipper snails or slipper limpets, cup-and-saucer snails, and Chinese hat snails are a family of small to medium-sized marine prosobranch gastropods...

, the slipper snails and cup and saucer snails.

Shell description

The shell

Gastropod shell

The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 of Crepidula onyx is up to 70 mm in length. The interior of the shell is glossy and is a strong tan to dark brown color, similar to the common colors of the mineral onyx

Onyx

Onyx is a banded variety of chalcedony. The colors of its bands range from white to almost every color . Commonly, specimens of onyx contain bands of black and/or white.-Etymology:...

. The "shelf" or "deck" is white.

The shell of this species can be distinguished from the shell of Crepidula adunca

Crepidula adunca

Crepidula adunca, common name the "hooked slippersnail" is a species of sea snail or "slipper snail", a marine gastropod mollusk in the family Calyptraeidae, the slipper snails and cup-and-saucer snails.- Distribution :...

by:

• Its larger size,
• The apex
  Apex (mollusc)
  Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
  
   is low and near the margin of the shell, curved to one side and not markedly hooked (rather than high, hooked and centrally placed),
• The interior shelf is notched at the ends, rather than curved forward at both ends, and
• The periostracum
  Periostracum
  The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
  
   is more prominent.

Distribution

The native range for this species is the Eastern Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 coast of the Americas, from Southern California

Southern California

Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...

 to Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

.

Nonindigenous distribution

The species has been introduced and is considered to be established in Puget Sound

Puget Sound

Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...

, Washington, since 2005.

Habitat

This species is common on rocks, shells, and pilings in protected bays, but it also lives in sheltered places on the open coast, occurring from the low intertidal zone

Intertidal zone

The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...

 to subtidal waters.