The little skate (''Leucoraja erinacea'') is a species of

skate Skate or Skates may refer to: Fish *Skate (fish), several genera of fish belonging to the family Rajidae * Pygmy skates, several genera of fish belonging to the family Gurgesiellidae * Smooth skates or leg skates, several genera of fish belongin ...

in the family Rajidae, found from

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

on sand or gravel

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. They are one of the dominant members of the

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

fish community in the northwestern Atlantic. This species is of minimal commercial importance and is mostly used as bait for

lobster trap A lobster trap or lobster pot is a portable trap that traps lobsters or crayfish and is used in lobster fishing. In Scotland (chiefly in the north), the word creel is used to refer to a device used to catch lobsters and other crustaceans. A l ...

s, though its wings are also marketed for food. It is also important as a

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

for biological and medical research.

Distribution and habitat

This skate is native to the western Atlantic Ocean, from

, Canada, to

Cape Hatteras Cape Hatteras is a cape located at a pronounced bend in Hatteras Island, one of the barrier islands of North Carolina. Long stretches of beach, sand dunes, marshes, and maritime forests create a unique environment where wind and waves shape ...

, USA. They are most abundant in the northern

Mid-Atlantic Bight The Mid-Atlantic Bight is a coastal region running from Massachusetts to North Carolina. It contains the New York Bight. It is separated from the South Atlantic Bight by Cape Hatteras to the south and the Gulf of Maine to the north by Cape Cod ...

and the

Georges Bank Georges Bank (formerly known as St. Georges Bank) is a large elevated area of the sea floor between Cape Cod, Massachusetts (United States), and Cape Sable Island, Nova Scotia (Canada). It separates the Gulf of Maine from the Atlantic Ocean. Th ...

. Little skates prefer sandy or gravelly habitats from the shore to a depth of , though they have been caught as deep as . They can tolerate temperatures of and

salinities Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

of 27–33.8 ppt (though the optimum is 29–33 ppt). They do not undertake long migrations, but at the inshore parts of the species' range individuals move into shallower water during the summer and deeper water during the fall and winter. At the southern extent of the range, many also move north and south with changing temperatures.Packer, D.B., Zetlin, C.A. and Vitaliano, J.J. (2003)
Essential Fish Habitat Source Document: Little Skate, ''Leucoraja erinacea'', Life History and Habitat Characteristics
''NOAA Tech Memo NMFS NE 175.'' Retrieved on March 14, 2009.

Description

The little skate has a rounded

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

disk 1.2 times as wide and as long, and a blunt

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is c ...

with a central tip. The

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s contain 38–66 series of round

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

on plates, adapted for grinding food. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s are divided into two parts, with the forward lobe modified into a leg-like structure. The

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...

is longer than the disk in juveniles and shorter in adults. Two small, closely spaced

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s are located near the tip of the tail. Adults have small

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s and usually no midline thorns, though there are strong spines on the dorsal surfaces of the head, shoulders, and tail. Males tend to have fewer spines than females. The coloration of the little skate ranges from grayish to uniform or variable shades of brown above, becoming lighter towards the edges of the disk, and white or gray below. Most individuals have small, round, dark spots on the back. The tail has irregular dusky blotches or a dark gray ventral surface. The little skate may be confused with unspotted individuals of the winter skate (''

Leucoraja ocellata The winter skate (''Leucoraja ocellata'') is a globally-endangered species of skate found in the surrounding waters of northeastern North America. They inhabit shallow shelf waters and are prone to bycatch during commercial fishing. Descripti ...

''), which has a similar shape. This species typically measures long, but may reach long. Little skates grow to a larger maximum size in the northern part of their range.

Biology and ecology

Little skates are more active at night and spend much of the day buried in sediment, usually near specific landscape features such as depressions excavated by other animals. They employ a curious mode of locomotion, dubbed " punting" by the first scientists to document it, to move over the sea floor. The forward lobes of the pelvic fins are modified into leg-like structures called "crura" (singular "crus"), containing three flexible joints and modified skeletal and muscular elements. The little skate pushes off the substrate with both crura and then glides a short distance on its wings while repositioning the crura for the next push. The crura are also used as pivots when the skate needs to turn. Research proposes that the locomotion is akin to that found in land vertebrates and thus puts the evolution of the underlying genes 20 million years earlier. It has been speculated that using the pelvic fins in this manner assists in hunting, by reducing water

turbulence In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

that might alert the prey or distort the ray's

electroreception Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stu ...

. The tail of the little skate contains an

electric organ An electric organ, also known as electronic organ, is an electronic keyboard instrument which was derived from the harmonium, pipe organ and theatre organ. Originally designed to imitate their sound, or orchestral sounds, it has since developed ...

that intermittently generates a weak electric field (the electric organ discharge or EOD). The EOD lasts 70 ms and has a head-negative monophasic

waveform In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.David Crecraft, David Gorham, ''Electronic ...

. This electric organ is thought to function in communication, and may help potential mates locate one another. Young and adult little skates are preyed upon by

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...

s, other skates, teleost fishes (including

cod Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...

goosefish Goosefishes are anglerfishes in the family Lophiidae found in the Arctic, Atlantic, Indian, and Pacific Oceans, where they live on sandy and muddy bottoms of the continental shelf and continental slope, to depths of more than . Like most other an ...

sea raven Sea ravens are a family, the ''Hemitripteridae'', of scorpaeniform fish. They are bottom-dwelling fish that feed on small invertebrates, found in the northwest Atlantic and north Pacific Oceans. They are covered in small spines (modified scales). ...

longhorn sculpin The longhorn sculpin (''Myoxocephalus octodecemspinosus'') is a Northwest Atlantic species of sculpin in the fish family Cottidae. It is a predatory and scavenging fish that can feed on the remains of other organisms. Appearance The longhorn s ...

bluefish The bluefish (''Pomatomus saltatrix'') is the only extant species of the family Pomatomidae. It is a marine pelagic fish found around the world in temperate and subtropical waters, except for the northern Pacific Ocean. Bluefish are known as ta ...

, and

summer flounder The summer flounder or fluke (''Paralichthys dentatus'') is a marine flatfish that is found in the Atlantic Ocean off the East Coast of the United States and Canada. It is especially abundant in waters from North Carolina to Massachusetts. De ...

gray seal The grey seal (''Halichoerus grypus'') is found on both shores of the North Atlantic Ocean. In Latin Halichoerus grypus means "hook-nosed sea pig". It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or " ...

s, androck crabs ('' Cancer irroratus''). Their egg-cases are preyed on by the

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

Strongylocentrotus droebachiensis ''Strongylocentrotus droebachiensis'' is commonly known as the green sea urchin because of its characteristic green color. It is commonly found in northern waters all around the world including both the Pacific and Atlantic Oceans to a northerly ...

'' and the

whelk Whelk (also known as scungilli) is a common name applied to various kinds of sea snail. Although a number of whelks are relatively large and are in the family Buccinidae (the true whelks), the word ''whelk'' is also applied to some other marine ...

Buccinum undatum ''Buccinum undatum'', the common whelk or the waved buccinum, is a large, edible marine gastropod in the family Buccinidae, the "true whelks".Fraussen, K.; Gofas, S. (2014). Buccinum undatum Linnaeus, 1758. Accessed through: World Register of M ...

''. Known

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s of the little skate include the

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

ns '' Caliperia brevipes'', '' Haemogregarina delagei'', and '' Trypanosoma rajae'', the

myxosporea Myxosporea is a class of microscopic parasites, belonging to the Myxozoa clade within Cnidaria. They have a complex life cycle which comprises vegetative forms in two hosts, an aquatic invertebrate (generally an annelid but sometimes a bryozoan) ...

ns '' Chloromyxum leydigi'' and '' Leptotheca agilis'', the

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

'' Pseudanisakis tricupola'', and the

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s '' Eudactylina corrugata'' and '' Lernaeopodina longimana''.

Feeding

The diet of the little skate consists mostly of decapod

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 and

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

Polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are mad ...

s are also an important prey item, while other

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s (including

isopod Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

sea squirt Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class (biology), class in the subphylum Tunicate, Tunicata of sac-like marine (ocean), marine invertebrate filter feeders. Ascidians ar ...

s, and

s) and small

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

fishes (including

sand lance A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lances are commonly known as "sand eels", though they are not related to true eels. Another variant name is launce, and all names of the fish are ...

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

cunner The cunner (''Tautogolabrus adspersus''), also known as the blue perch, bergall, chogset, choggie, conner or sea perch, is a species of wrasse native to the northwestern Atlantic, where it is found from the Gulf of St. Lawrence and Newfoundland ...

s, and

) are rarely taken. The importance of crustaceans in the skate's diet increases with size. This species shares its benthic habitat with the similar winter skate; the little skate focuses more on epifauna (organisms living atop the substrate) while the winter skate eats more infauna (burrowing organisms). The little skate has an extremely high number of electrosensory

ampullae of Lorenzini Ampullae of Lorenzini (singular ''Ampulla'') are electroreceptors, sense organs able to detect electric fields. They form a network of mucus-filled pores in the skin of cartilaginous fish (sharks, rays, and chimaeras) and of basal actinopterygia ...

around its mouth, giving it a high degree of spatial precision when hunting for prey buried in the substrate.

Reproduction

Little skates are

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

. Mating occurs frequently throughout the year and pregnant females can be found year-round. However, eggs are most common from October to December and from April to May, and least common from August to September and February to March. An average little skate spawns twice a year, in spring and fall, and produces a total of 10–35 eggs annually. Females deposit their egg capsules in pairs on sandy bottoms, in water no more than deep. The egg cases are amber-colored when first laid but become greenish-brown and leathery. Each roughly rectangular case contains a single fertilized egg and measures long and wide. There are hollow horns at each corner with sticky tendrils to secure the egg case to the substrate; the anterior horns are half as long as the case and curved inward, while the posterior horns are as long as the case and nearly straight. Eggs raised in captivity hatch in 5–6 months, while those in the wild may take up to 12 months to hatch, depending on temperature. While inside the case, the

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 ...

s have a whip-like extension on the tail believed to be used for circulating water. The newborns measure long and are perfectly formed miniatures of the adults. After hatching, the empty egg capsules often wash ashore and are known as "

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 ...

s". Growth is about per year for the first three years, then slows down to per year between the third and fourth years. At adolescence, males become larger than the females, and this difference persists through adulthood. Males mature at long and females at long. Very few little skates over 5 years old have been found, suggesting a high

mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of de ...

at that age. An unusual little skate specimen found off

Fishers Island, New York Fishers Island (Pequot: ''Munnawtawkit'') is an island that is part of Southold, New York, United States at the eastern end of Long Island Sound, off the southeastern coast of Connecticut across Fishers Island Sound. About long and wide, it ...

contained a developed

testis A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

vas deferens The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube ...

, and functional

clasper 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 c ...

on its left side and an adolescent

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

, shell gland,

oviduct The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, o ...

, and abortive clasper on its right. This example of

hermaphroditism In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separ ...

(a bilateral

gynandromorph A gynandromorph is an organism that contains both male and female characteristics. The term comes from the Greek γυνή (''gynē'') 'female', ἀνήρ (''anēr'') 'male', and μορφή (''morphē'') 'form', and is used mainly in the field ...

) is one of very few known for

elasmobranch Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of gil ...

fishes.

Human interactions

Euell Gibbons Euell Theophilus Gibbons (September 8, 1911 – December 29, 1975) was an outdoorsman and early health food advocate, promoting eating wild foods during the 1960s. Early career Gibbons was born in Clarksville, Texas, on September 8, 1911, a ...

promoted the consumption by humans of the little skate in his

cookbook A cookbook or cookery book is a kitchen reference containing recipes. Cookbooks may be general, or may specialize in a particular cuisine or category of food. Recipes in cookbooks are organized in various ways: by course (appetizer, first cour ...

''Stalking the Blue-eyed Scallop'' (1964), noting that its wings, properly cut, could be treated like

scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...

s. Round cuts from the little skate's wings are marketed as "scallops", though due to their small size their commercial importance is limited. Little skates are also often used to bait traps, especially for

lobsters Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...

and

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

s.Kittle, K
Biological Profiles: Little Skate
''Florida Museum of Natural History Ichthyology Department''. Retrieved on March 14, 2009. Skates are typically caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

otter trawl Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towin ...

s; the little skate is not currently considered to be

overfished Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in the ...

. Along with the

spiny dogfish The spiny dogfish (''Squalus acanthias''), spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family (biology), family of sharks, which is part of the Squaliformes order. While these common names ma ...

(''Squalus acanthias''), the little skate is often used as a

in biomedical research. A BAC genomic library for the little skate was completed in January 2005.Barnes, D. (2008)
The Skate (''Leucoraja erinacea'') Genome Project
.

MDI Biological Laboratory The MDI Biological Laboratory (MDIBL), formerly known as Mount Desert Island Biological Laboratory is an independent non-profit biomedical research institution founded in 1898 and located in Salisbury Cove, Maine, on Mount Desert Island. Its mi ...

. Retrieved on August 19, 2010.

References

External links

Little Skate
at th
Florida Museum of Natural History Ichthyology DepartmentVideos of little skates "punting"
a
David M. Koester's webpage
* F. Giardina, L. Mahadevan
Models of benthic bipedalism
Journal of the Royal Society Interface, Volume 18, Issue 174, 13 January 2021. doi:10.6084/m9.figshare.c.5250907. See also :: Carly Cassella
Ancient Vertebrates May Have Had Tools For Walking Long Before They Left The Ocean
On: science^alert, 19 March 2021. Gif and Video included. {{DEFAULTSORT:skate, little

little skate The little skate (''Leucoraja erinacea'') is a species of Skate (fish), skate in the family Rajidae, found from Nova Scotia to North Carolina on sand or gravel habitats. They are one of the dominant members of the demersal fish community in the n ...

Natural history of Nova Scotia Fauna of the Northeastern United States Fish of the Eastern United States