The roundel skate or Texas clearnose skate (''Rostroraja texana'') 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 ...

cartilaginous Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and ...

fish in the family Rajidae. It is found in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

, Southeast

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

and the Yucatan Peninsula.

Description

The disc of the roundel skate is diamond-shaped. The short rounded snout has a clear area of skin on either side. The rest of the dorsal surface is an unblotched chocolate brown colour, although sometimes there are darker patches. A pair of distinctive dark eyespots with pale pink rims lie on either side of the middle of the dorsal surface (these may confuse potential

predators Predation is a biological interaction where 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 the ...

). A row of thorns runs along the midline of the back, but there are no venomous spines. The medium-length tail has a short dorsal fin near its tip and a small caudal fin. Males become mature at about 5 years old at a length of about , while females are mature a year later at a length of about .

Distribution and habitat

The roundel skate is native to the southeastern coast of Florida, the Gulf of Mexico and the

Campeche Bank Campeche Bank is part of the Gulf of Mexico and extends from the Yucatan Straits in the east to the Tabasco-Campeche Basin in the west.Campeche Bankin Geonames.org (cc-by)/ref> The Campeche ocean bank is from Mexico's geography of Campeche naut ...

, a shallow area of sea off the northern coast of the Yucatan Peninsula. It usually occurs on sand, crushed shell or shingle to depths of about .

Biology

Adult roundel skates feed predominantly on

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

(65%), but also take fish (25%) and sometimes

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s and other

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. The diet of juveniles is over 90% shrimp, with the rest composed of small fish. The roundel skate is sexually dimorphic, with the males usually being smaller than the females. In reproduction, the male's

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's ...

are inserted into the female's

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

, and fertilisation is internal. As the fertilised egg passes down the uterus, albumen and yolk are added and it is placed in a rectangular

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

ous egg case known as a

mermaid's purse An egg case or egg capsule, often colloquially called a mermaid's purse, is the casing that surrounds the eggs of oviparous sharks, skates and chimaeras. Egg cases typically contain one embryo, except for big skate and mottled skate egg cases ...

. This is pale brown, flat on one side and rounded on the other, with tendrils at the corners. The developing

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

feeds on the

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

, and some months later emerges as a fully formed juvenile fish about long.

Status

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has classified this fish as "Least Concern" in its

Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

References

{{Taxonbar, from=Q5845338 roundel skate Fauna of the Southeastern United States Fish of the Gulf of Mexico Least concern biota of North America Least concern biota of the United States roundel skate