Scyliorhinus retifer

Geographic Range

Scyliorhinus retifer , the chain catshark, is found in the northwest and western Central Atlantic Ocean, the Carribean Sea, the Gulf of Mexico and the continental shelfe along the northeastern United States. It is most abundant in the deeper waters off of Virginia and North Carolina.

• Biogeographic Regions
• atlantic ocean atlantic ocean
  • native native

Habitat

Chain catsharks live in subtropical waters, with temperatures between 8.5 and 11.3ºC. They inhabit depths generally between 75 and 550 m, though in the northern part of their range they are found between 36 and 230 m. In southern areas they inhabit waters deeper than 460 m. Scyliorhinus retifer is found from 45ºN to 15ºN and 99ºW to 64ºW. This is essentially the outer continental shelf and upper slope of the western Atlantic and Gulf of Mexico. The favored bottom is rough and rocky.

• Habitat Regions
• temperate temperate
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• coastal coastal

Physical Description

Scyliorhinus retifer has a slender body that is somewhat wedge-shaped, with a blunt snout narrowing to a slender tail. There is a space between the second dorsal fin and the caudal fins; the first dorsal fin sits slightly behind the level of the base of the pectoral fins. Body length normally reaches about 47 cm in females and 48 cm in males. In one sample catch, most animals measured in the range of 41 to 45 cm, weighing 300 to 380 g. Chain catsharks have smooth skin that is tannish brown, often with a hint of yellow, and with brownish-black chainlike markings on the body and dorsal fins, giving them their common name. The skin is embedded with small denticles. They have yellowish-green eyes.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Development

Scyliorhinus retifer eggs are at the blastodisc stage when laid. In early stages, the embryo lies on its left side - there is no known reason for this. When Scyliorhinus retifer young reach 10 mm in length, they have well-defined gill arches and there is a clear roof over the medula. They continue to grow until they reach 74 mm in length, when they are fully developed in shape (though not in size). The yolk sac is still large at this stage.

In the laboratory, hatching occurred at 100 to 110 mm, with an average incubation time of 256 days (+/- SD 8 d, N = 62) at 11.7 to 12.8ºC. In natural habitats, however, it is thought to take up to a year due to colder ambient temperatures.

Reproduction

A male and female generally swim together, and after some time the male bites the female near the tail. He then gradually moves his grip forward until he can wrap himself around the female. He wraps himself around the female's pectoral fin, body, tail, and gills. Copulation ensues.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Chain catsharks are oviparous breeders, non-guarders, and open water/substrate embryo-scatterers. Females lay two embryos at a time after an unknown gestation period. The embryos are deposited in an egg case (also called a "mermaid's purse") with tendrils at the 4 corners. Mating generally occurs in areas where there are structures such as sponges, gorgonians, or manmade structures, as females use these to deposit embryos. They swim around a structure with tendrils flowing behind until the tendrils wrap around the structure and the embryos are thus attached. The embryos emerge from their egg case about 250 days later. Developing embryos in egg cases have been collected in February in the Chesapeak Bay, suggesting that breeding may occur in late winter or early spring. It is thought that chain catsharks become sexually mature at 8 to 9 years old.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• ovoviviparous ovoviviparous

After gestation of the eggs and deposition of embryos by the female, there is no parental investment by Scyliorhinus retifer . The embryo is left on its own, and it feeds from the yolk sac until it emerges from the egg case.

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

There is no data regarding the lifespan of Scyliorhinus retifer , although certain captive Scyliorhinus retifer were at least nine years old at time of writing.

Behavior

Chain catsharks are not exceptionally active sharks. They usually remains motionless among structures along the sea bottom, including rocks and man-made structures, swimming occasionally when hunting prey. There is little available information on activity patterns, sociality, or movements.

• Key Behaviors
• natatorial natatorial
• motile motile
• sedentary sedentary

Home Range

There is no information on home range available.

Communication and Perception

There is no data available describing the communication and/or perception of Scyliorhinus retifer . However, as with most sharks, these catsharks are likely to have sensitive tactile and chemoreception that they use extensively in foraging.

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Scyliorhinus retifer preys mostly on animals such as squid, fish, annelids, and crustaceans. In a gut content analysis of 81 specimens (both juveniles and adults), 96% had food in their stomachs. Furthermore, 64% had squid beaks or remains, 55% had bony fish remains, 32% had polychaetes or other annelids, and 21% had crustacean remains.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic or marine worms
• aquatic crustaceans

Predation

There was no available data on the predators of Scyliorhinus retifer . It is assumed that large, piscivorous fish and sharks prey on chain catsharks.

Ecosystem Roles

Scyliorhinus retifer takes part in the food chain by preying on macrofauna such as squid, fish, annelids, and crustaceans. It can be reasonably conjectured that it is in turn preyed on by other species, such as large, piscivorous fish and larger sharks.

Economic Importance for Humans: Positive

Scyliorhinus retifer is sometimes taken as "bycatch" in trawling fisheries, but there is no interest in these sharks commercially. They are popular in aquaria because of their small size and patterned bodies.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

There is no known negative economic impact of Scyliorhinus retifer on humans. These are small and docile sharks.

Conservation Status

Chain catsharks are considered "least concern" by the IUCN and are not protected by other regulatory agencies.

Other Comments

Chain catsharks are also known as chain dogfish and alitán mallero. Chain catshark is considered the most appropriate English name, as they belong to a group of sharks called "catsharks."

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Mark Bond (author), University of Notre Dame, Karen Powers (editor, instructor), Radford University.

References

Bester, C. 2005. "Chain dogfish" (On-line). Ichthyology at the Florida Museum of Natural History. Accessed September 13, 2008 at http://www.flmnh.ufl.edu/fish/Gallery/Descript/ChainDogfish/ChainDogfish.html .

Carpenter, K., S. Luna, K. Kesner-Reyes. 2006. "Scyliorhinus retifer" (On-line). Fishbase. Accessed September 13, 2006 at http://fishbase.org/Summary/speciesSummary.php?ID=853&genusname=Scyliorhinus&speciesname=retifer .

Castro, J., N. Overstrom, P. Bubucis. 1988. The Reproductive Biology of the Chain Dogfish, Scyliorhinus retifer. Copeia , 3: 740-746.

National Center for Biotechnology Information, 2006. "Scyliorhinus retifer" (On-line). Accessed March 21, 2006 at http://www.ncbi.nlm.nih.gov/Taxononmy/Browser/wwwtax.cgi?id=107947 .

Schwartz, F. 2003. Sharks, Skates, and Rays of the Carolinas . Chapel Hill and London: The University of North Carolina Press.