Lady crab
Encyclopedia
Ovalipes ocellatus is a species
of crab
from eastern North America
, known as the lady crab, calico crab or ocellated crab. It has a shell 3 in (7.6 cm) long and only slightly wider, which is covered in clusters of purple spots. It occurs from Canada
to Georgia
, and lives mainly on molluscs, such as the Atlantic surf clam
.
of O. ocellatus is slightly wider than long, at 8.9 centimetres (3.5 in) wide, and 7.5 cm (3 in) long. This distinguishes it from other crabs in the family Portunidae
, which often have elongated lateral spines. The carapace is yellow-grey or light purplish, with "leopardlike clusters of purple dots", and 3–5 spines along the edge behind each eye. O. ovalipes is almost identical to O. floridanus, which lives in the Gulf of Mexico
, but can be separated from the sympatric
O. stephensoni by the purple spots, which O. stephensoni lacks.
to Georgia
. O. ocellatus is "probably the only Ovalipes species common north of Virginia", being replaced by Ovalipes stephensoni to the south.
l stages, lasting a total of 18 days at 25 °C (77 °F) and a salinity
of 30‰, and 26 days at 20 °C (68 °F) and 30‰.
, particularly the Atlantic surf clam
Spisula solidissima.
in 1799, as Cancer ocellatus. In 1898, Mary Jane Rathbun
moved the species to her new genus Ovalipes
.
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 crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
from eastern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, known as the lady crab, calico crab or ocellated crab. It has a shell 3 in (7.6 cm) long and only slightly wider, which is covered in clusters of purple spots. It occurs from Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
to Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
, and lives mainly on molluscs, such as the Atlantic surf clam
Atlantic surf clam
The Atlantic surf clam, also referred to as the "bar clam," "hen clam," "skimmer," or simply as the "sea clam," is a western Atlantic surf clam, a very large , edible, saltwater clam or marine bivalve mollusk in the family Mactridae...
.
Description
The carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
of O. ocellatus is slightly wider than long, at 8.9 centimetres (3.5 in) wide, and 7.5 cm (3 in) long. This distinguishes it from other crabs in the family Portunidae
Portunidae
Portunidae is a family of crabs which contains the swimming crabs.-Description:Portunid crabs are characterised by the flattening of the fifth pair of legs into broad paddles, which are used for swimming...
, which often have elongated lateral spines. The carapace is yellow-grey or light purplish, with "leopardlike clusters of purple dots", and 3–5 spines along the edge behind each eye. O. ovalipes is almost identical to O. floridanus, which lives in the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
, but can be separated from the sympatric
Sympatry
In biology, two species or populations are considered sympatric when they exist in the same geographic area and thus regularly encounter one another. An initially-interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation...
O. stephensoni by the purple spots, which O. stephensoni lacks.
Distribution
The distribution of O. ocellatus extends from CanadaCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
to Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
. O. ocellatus is "probably the only Ovalipes species common north of Virginia", being replaced by Ovalipes stephensoni to the south.
Life cycle
O. ocellatus has five larvaLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
l stages, lasting a total of 18 days at 25 °C (77 °F) and a salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
of 30‰, and 26 days at 20 °C (68 °F) and 30‰.
Ecology
O. ocellatus is a nocturnal predator, which often buries itself in the sand. It has been described as "vicious" and "the crab most likely to pinch a wader's toes". It feeds mostly on molluscsMollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
, particularly the Atlantic surf clam
Atlantic surf clam
The Atlantic surf clam, also referred to as the "bar clam," "hen clam," "skimmer," or simply as the "sea clam," is a western Atlantic surf clam, a very large , edible, saltwater clam or marine bivalve mollusk in the family Mactridae...
Spisula solidissima.
Taxonomic history
O. ocellatus was first described by Johann Friedrich Wilhelm HerbstJohann Friedrich Wilhelm Herbst
Johann Friedrich Wilhelm Herbst was a German naturalist and entomologist from Petershagen, Minden-Ravensberg....
in 1799, as Cancer ocellatus. In 1898, Mary Jane Rathbun
Mary Rathbun
Mary J. Rathbun was an American zoologist who specialized in crustaceans. She worked at the Smithsonian Institution, often unaided, from 1884 until her death...
moved the species to her new genus Ovalipes
Ovalipes
Ovalipes is a genus of crabs in the family Portunidae, containing 11 extant species:*Ovalipes australiensis Stephenson & Rees, 1968*Ovalipes catharus *Ovalipes elongatus Stephenson & Rees, 1968...
.