Clearnose skate

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Clearnose skate
Raja eglanteria (S0848) (12656857295).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Batoidea
Order: Rajiformes
Family: Rajidae
Genus: Rostroraja
Species:
R. eglanteria
Binomial name
Rostroraja eglanteria
Synonyms [2]
  • Raia chantenayLesueur, 1824
  • Raia desmarestiaLesueur, 1824
  • Raja diaphanesMitchill, 1815
  • Raja eglanteriaBosc, 1800

The clearnose skate (Rostroraja eglanteria) is a species of cartilaginous fish in the family Rajidae. R. eglanteria is also known by other common names such as the brier skate and summer skate. [3] Clearnose skates are easily identified by the translucent patches on either side of their snouts and their mottled dorsal surface. They are found along the Atlantic and Gulf coasts of the United States in shallow waters of the continental shelf. [4]

Contents

Taxonomy

Clearnose skates are elasmobranchs in the order Rajiformes and family Rajidae. They were one of nearly thirty members of the genus Raja before redesignation based on DNA analysis in 2016. Clearnose skates were first described as Raja eglanteria by Bosc in 1800. [2] Other scientific names include R. chantenay, R. desmarestia, and R. diaphanes; [2] however, these names rarely appear in the literature.

Description

Clearnose skates are named for the characteristic light-colored to translucent patches along both sides of the rostrum. [5] The dorsal surface is primarily brown to grey in color, while the ventral surface is white. The dorsal side of the pectoral fins also exhibits dark brown to black bars and spots. [5]

R. eglanteria has a roughly rhombic disc shape, with the snout and pectoral fins making an approximate right angle. Mature clearnose skates reach up to 79 cm (31 in) in total length and 52 cm (20 in) in width. [6] The tail is approximately half the total length. [5]

Another notable characteristic of clearnose skates is their line of thorns along the middle of the back and tail. [7] The remainder of the dorsal surface is covered in small prickles, yielding the common name of brier skate. [8] These prickles are concentrated on the anterior portion of the disc, as well as along the spine, like the thorns. [8]

Habitat and distribution

The range of R. eglanteria includes the eastern coast of the United States, with its northernmost range in Massachusetts and southernmost in Florida. The clearnose skate's range then extends around the Florida peninsula to the eastern and north portions of the Gulf of Mexico. [4]

Like other skate species, clearnose skates are demersal. They can be found on soft substrates like mud and sand, or on harder surfaces like rock and gravel. [9]

Clearnose skates prefer shallow water that is at least partially saline (≥22 ppt). [9] These skates are most commonly found at depths less than 111 m, but can be in waters as deep as 330 m. [4] Skate depth is dependent on season, with R. eglanteria located primarily more inland during the winter and spring and offshore during the summer and fall. [10]

R. eglanteria can be found in water anywhere from 41 to 86 °F (5 to 30 °C). [5] [9] Preferred temperature ranges are dependent on latitude, with skates in the northern regions of their range tolerating a larger temperature range than their southern counterparts. [9]

Biology

Feeding

The diet of clearnose skates includes crustaceans and molluscs, such as shrimp and fiddler crabs, as well as small fish. [3] Hunting occurs primarily at night, with the skates searching along the seafloor for food. [11]

Clearnose skates have 46 to 54 teeth in their upper jaw and approximately the same number in their lower jaw. [3] These teeth are blunt, small, and close together, enabling the skate to crush the hard shells of its prey. Male clearnose skates have sharper teeth than females, although this is probably to aid in copulation rather than feeding.

Behavior

Like other batoids, clearnose skates exhibit walking, or "punting," along the benthic substrate using their modified pelvic fins. [12] [13] To propel itself forward via punting, a skate first anchors its pelvic fin into the seafloor and then pushes the fin toward its tail. During this action, the rest of the body of the skate remains motionless. [13] Another form of swimming locomotion in R. elganteria is through the undulation of the pectoral fins. [14]

Orientation and position of the skate, whether during swimming, punting, or hunting, is determined using neuromasts, which are a primary component of the lateral line. [15]

Reproduction

Copulation

The courtship ritual of clearnose skates was observed and well-documented by Luer and Gilbert: [16]

Typically the male grasps the trailing edge of the female's pectoral fin in his jaws when both are resting on their ventral surface in the pool or tank . Following this action, he swings his tail beneath her pelvic fin and tail, flexes one clasper medially and inserts it into her cloacal aperture . Prior to and during insertions, the clasper is lubricated from secretions of the clasper gland . The process of insertion is slow and methodical during which time the male repeatedly thrusts his clasper slowly forward up into the female's genital tract . Sometimes it takes an hour or more before the clasper is fully inserted.

Eggs

Clearnose skates are oviparous, and therefore they lay fertilized eggs, commonly referred to as Mermaid's purses. Each corner of the rectangular egg case has a small curved horn. [16] The size of the egg case ranges from 6.4 to 7.7 cm (2.5 to 3.0 in) long and 3.7 to 4.7 cm (1.5 to 1.9 in) wide. [16]

Egg deposition occurs in pairs, and up to 30 pairs may be laid by a female. As the female lays the egg, the longer anterior horns emerge first. The shorter posterior horns follow and enable the egg case to anchor to the substrate, as they are covered in a sticky substance. [16]

At first, the embryo is completely enclosed within the egg case. As it develops, a small hole (called the respiratory canal) along the base of the horns opens, allowing seawater to enter the case. The flow of seawater is maintained by the tail beating of the embryo. [16]

Embryonic clearnose skates demonstrate a ventilatory freeze response when a weak low-frequency electric field is imposed upon the egg capsule. This freeze behavior will cause the egg-encapsulated embryonic skates to stop ventilatory streaming. This will decrease the likelihood of sensory detection, and thus “cloak” embryos from searching egg predators. [17]

Life cycle

The clearnose skate life cycle starts when a female deposits an egg. The embryo begins to enlarge as its cells divide. [18] As division occurs, regionalization of the skate can be observed, with head and tail regions. Development continues with the formation of neural components, as well as spiracles and gill filaments. Other structures and organs continue to differentiate and grow, and finally the mottled pattern of the dorsal surface is developed. [18]

The embryos incubate within the egg case for approximately 12 weeks. Eventually, the embryo grows too large for the egg case, and will then break free by extending its pectoral fins and tail. Hatchlings are approximately 13 to 15 cm (5.1 to 5.9 in) in total length and 8.4 to 10.5 cm (3.3 to 4.1 in) in disc width. [16]

Age of maturity ranges between two and six years, depending on sex, with females taking longer to mature than males. [4] The size of mature male skates is a minimum of 56 cm (22 in), and of females 59 cm (23 in). [19]

Human interaction

Clearnose skates are not commonly targeted in commercial fishing due to their small size; however, these skates are captured as bycatch, especially in trawling. [4]

Related Research Articles

<span class="mw-page-title-main">Skate (fish)</span> Family of fishes

Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera. Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae, but are now considered as distinct families. Alternatively, the name "skate" is used to refer to the entire order of Rajiformes.

<span class="mw-page-title-main">Rajiformes</span> Order of fishes in the superorder Batoidea

Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule.

<span class="mw-page-title-main">Cloudy catshark</span> Species of shark

The cloudy catshark is a common species of catshark, belonging to the family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of 320 m (1,050 ft). Growing up to 50 cm (20 in) long, this small, slim shark has a narrow head with a short blunt snout, no grooves between the nostrils and mouth, and furrows on the lower but not the upper jaw. It is also characterized by extremely rough skin and coloration consisting of a series of dark brown saddles along its back and tail, along with various darker and lighter spots in larger individuals.

<i>Raja</i> (fish) Genus of cartilaginous fishes

Raja, also known as raia, is a genus of skates in the family Rajidae containing 16 species. Formerly a wastebasket genus, many species historically categorized here have been moved to other genera in the family, such as Amblyraja, Beringraja, Dipturus, Leucoraja and Rostroraja. Raja are flat-bodied, cartilaginous fish with a rhombic shapes due to their large pectoral fins extending from or near from the snouts to the bases of their tails. Their sharp snouts are produced by a cranial projection of rostral cartilage. The mouth and gills are located on the underside of the body. They may be either solid-coloured or patterned, and most skates have spiny or thorn-like structures on the upper surface, while some species contain weak electrical organs within their tails. Mating typically occurs in the spring and the female lays numerous eggs per clutch which are encapsulated in leathery cases, commonly known as "mermaid’s purses". Species vary in size, ranging from about 40 to 140 cm (1.3–4.6 ft) in length. These bottom-dwellers are active during both day and night, and typically feed on molluscs, crustaceans and fish. Raja skates are found in the East Atlantic, also in the Mediterranean, and western Indian Ocean, ranging from relatively shallow water to a depth of 800 m (2,600 ft). Skates and related species have fossil records dating from the Upper Cretaceous period, thus this well-adapted species is quite ancient.

<span class="mw-page-title-main">Smooth butterfly ray</span> Species of fish

The smooth butterfly ray is a species of cartilaginous fish in the family Gymnuridae. It is a member of the order Myliobatiformes, which contains 10 total families. Its natural habitats are shallow seas, subtidal aquatic beds, estuarine waters, and coastal saline lagoons. Its common name is derived from its compressed body, pectoral fins that are wider than their length, and overall diamond shape.

<span class="mw-page-title-main">Thornback ray</span> Species of cartilaginous fish

The thornback ray, or thornback skate, is a species of ray fish in the family Rajidae.

<span class="mw-page-title-main">Big skate</span> Species of cartilaginous fish

The big skate is the largest species of skate in the waters off North America. They are found along the Pacific Coast from Alaska to Baja California, typically from the intertidal zone to a depth of 120 m (390 ft), and feed on benthic invertebrates and small fishes. They are unusual among skates in that their egg cases may contain up to seven eggs each. This species is one of the most commercially important skates off California and is sold for food.

<span class="mw-page-title-main">Bottlenose skate</span> Species of cartilaginous fish

The bottlenose skate, spearnose skate, or white skate is a species of skate in the family Rajidae. It is a benthic fish native to the coastal eastern Atlantic Ocean. Due to overfishing, it has been depleted or extirpated in many parts of its former range in the northeastern Atlantic and the Mediterranean Sea, and is now endangered.

<span class="mw-page-title-main">Little skate</span> Species of cartilaginous fish

The little skate is a species of 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 northwestern Atlantic. This species is of minimal commercial importance and is mostly used as bait for lobster traps, though its wings are also marketed for food. It is also important as a model organism for biological and medical research.

<span class="mw-page-title-main">Mottled skate</span> Species of cartilaginous fish

The mottled skate is a species of skate in the family Rajidae. An inhabitant of shallow coastal waters, it is found in the northwestern Pacific Ocean off Korea, Japan, and China. This species grows to 1.12 m (3.7 ft) long and has a diamond-shaped pectoral fin disc with a long snout. It is characterized by a covering of prickles above and below its snout, but not elsewhere on its body, and a dark ring in the middle of each "wing".

The Korean skate is a skate in the family Rajidae, and is the sole member of the genus Hongeo. It was previously classified in the genus Raja as Raja koreana until discoveries identified this species as a member of a distinct genus. It is considered Critically Endangered on the IUCN Red List due to overexploitation.

<span class="mw-page-title-main">Pita skate</span> Species of cartilaginous fish

The pita skate is a medium-sized skate in the family Rajidae. The holotype and only known specimen was found in the northern Persian Gulf, in Iraqi waters. It was collected at a depth of less than 15 m (49 ft).

<i>Rostroraja texana</i> Species of cartilaginous fish

The roundel skate or Texas clearnose skate is a species of cartilaginous fish in the family Rajidae. It is found in the Gulf of Mexico, Southeast Florida and the Yucatan Peninsula.

Dipturus teevani, commonly known as the prickly brown ray or Caribbean skate, is a species of cartilaginous fish in the family Rajidae. The prickly brown ray is medium in size compared to other skates, and is known from a patchy, deep-water distribution in the western Atlantic Ocean.

<i>Raja stellulata</i> Species of cartilaginous fish

Raja stellulata, commonly known as the Pacific starry skate, rock skate, prickly skate, or starry skate, is a species of cartilaginous fish in the family Rajidae. It is found on rocky bottoms at 18–982 m depths in the Northeast and Eastern Central Pacific, from Coronado Bank in northern Baja California in Mexico to Barkley Sound in British Columbia, Canada. Females reach a maximum total length of 76.1 cm and a maximum age of 15 years, while males can be up to 71.7 cm long and live up to 14 years; the total length at birth is 15.5–22.5 cm. This skate prefers cold water with a temperature of 4.1–11.6°C.

Batoids are a superorder of cartilaginous fish consisting of skates, rays and other fish all characterized by dorsoventrally flattened bodies and large pectoral fins fused to the head. This distinctive morphology has resulted in several unique forms of locomotion. Most Batoids exhibit median paired fin swimming, utilizing their enlarged pectoral fins. Batoids that exhibit median paired fin swimming fall somewhere along a spectrum of swimming modes from mobuliform to rajiform based on the number of waves present on their fin at once. Of the four orders of Batoidae this holds truest for the Myliobatiformes (rays) and the Rajiformes (skates). The two other orders: Rhinopristiformes and Torpediniformes exhibit a greater degree of body caudal fin swimming.

<i>Raja radula</i> Ray in the genus Raja

The rough ray is a Mediterranean ray species of the Rajidae family described by Delaroche in 1809.

<span class="mw-page-title-main">Blonde ray</span> Species of cartilaginous fish

The blonde ray or blonde skate is a species of ray fish in the family Rajidae.

The deepwater ray, also called the deepwater skate or abyssal skate, is a species of skate in the family Rajidae.

Okamejei panayensis is a demersal fish belonging to the skate family, occurring in nearshore temperate environments and deep-water tropical and boreal regions.

References

  1. ↑ Anderson, B.; Kulka, D.W.; Herman, K.; Pacoureau, N. & Dulvy, N.K. (2020). "Rostroraja eglanteria". IUCN Red List of Threatened Species . 2020: e.T161658A124523079. doi: 10.2305/IUCN.UK.2020-3.RLTS.T161658A124523079.en . Retrieved 10 August 2023.
  2. 1 2 3 Bailly, Nicolas (2022). "Raja eglanteria Bosc, 1800". WoRMS. World Register of Marine Species.
  3. 1 2 3 "Raja eglanteria :: Florida Museum of Natural History". flmnh.ufl.edu. Retrieved 13 March 2016.
  4. 1 2 3 4 5 D. Ha, C. Luer & J. Sulikowski (2009). "Raja eglanteria". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature.
  5. 1 2 3 4 Elbert, D. A. and M. F. W. Stehmann. Sharks, Batoids and Chimaeras of the North Atlantic. FAO Species Catalogue for Fishery Purposes No. 7. Rome, 2013. pp 364-365.
  6. ↑ Carpenter, K.E. (ed.). The living marine resources of the Western Central Atlantic. Volume 1: Introduction, molluscs, crustaceans, hagfishes, sharks, batoid fishes, and chimaeras. FAO Species Identification Guide for Fishery Purposes and American Society of Ichthyologists and Herpetologists Special Publication No. 5. Rome, FAO. 2002. pp. 1-600.
  7. ↑ Lippson, A. J. and R. L. Lippson. 2006. Life in the Chesapeake Bay. 3rd ed. Baltimore: Johns Hopkins University Press. p 279.
  8. 1 2 Bigelow, H. B. and W. C. Schroder. 1953. Fishery bulletin of the fish and wildlife service 53. Pp. 65. http://www.gma.org/fogm/Raja_eglanteria.htm
  9. 1 2 3 4 Packer DB, Zetlin CA, Vitaliano JJ. 2003. Essential fish habitat source document: Clearnose skate, Raja eglanteria, life history and habitat characteristics. NOAA Tech Memo NMFS NE 174; 1-50.
  10. ↑ New England Fishery Management Council (NEFMC). 2003. Final fishery management plan (FMP) for the Northeast skate complex. National Marine Fisheries Service. pp 25
  11. ↑ Alden, P., B. Cassie, J. D. W. Kahl, E. A. Oches, H. Zirlin, and W. B. Zomlefer. 1999. National Audubon Society Field Guide to the Mid-Atlantic States. New York: Chanticleer Press. p 239.
  12. ↑ Lucifora, Luis O.; Vassallo, Aldo I. (1 September 2002). "Walking in skates (Chondrichthyes, Rajidae): anatomy, behaviour and analogies to tetrapod locomotion". Biological Journal of the Linnean Society. 77 (1): 35–41. doi: 10.1046/j.1095-8312.2002.00085.x . hdl: 11336/128800 . ISSN   1095-8312.
  13. 1 2 Macesic, L. J. and S. M. Kajiura. 2010. Comparative punting kinematics and pelvic fin musculature of benthic batoids. Journal of Morphology 271: 1219-1228
  14. ↑ Rosenberger, L. J. 2001. Pectoral fin locomotion in batoid fishes: undulation versus oscillation. Journal of Experimental Biology 204: 379-394
  15. ↑ Klimley, A. Peter (31 July 2013). The Biology of Sharks and Rays. University of Chicago Press. ISBN   978-0226442495.
  16. 1 2 3 4 5 6 Luer, C. A. and P. W. Gilbert. 1985. Mating behavior, egg deposition, incubation period, and hatching behavior in the clearnose skate, Raja eglanteria. Environmental Biology of Fishes 13(3): 161-171.
  17. ↑ Sisneros, & Tricas, T. C. (2002). Neuroethology and life history adaptations of the elasmobranch electric sense. Journal of Physiology, Paris, 96(5), 379–389. https://doi.org/10.1016/S0928-4257(03)00016-0
  18. 1 2 Luer, C. A., C. J. Walsh, A. B. Bodine, and J. T. Wyffels. 2007. Normal embryonic development in the clearnose skate, Raja eglanteria, with experimental observations on artificial insemination. Environmental Biology of Fishes 80: 239-255.
  19. ↑ Sosebee, K. A. 2004. Maturity of skates in northeast United States waters. Journal of Northwest Atlantic Fishery Science 35: 141-153.
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