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 ; tactile ; chemical
There was no available data on the predators of Scyliorhinus retifer. It is assumed that large, piscivorous fish and sharks prey on chain catsharks.
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.
Range mass: 300 to 380 g.
Range length: 48 (high) cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: male larger
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.
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.
Range depth: 460 to 36 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: coastal
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 (Native )
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.
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Molluscivore )
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.
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
There is no known negative economic impact of Scyliorhinus retifer on humans. These are small and docile sharks.
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.
Chain catsharks are considered "least concern" by the IUCN and are not protected by other regulatory agencies.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
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."
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)
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.
Breeding interval: Breeding intervals are not known.
Breeding season: Seasonality of breeding is poorly known throughout most of the range of chain catsharks.
Range number of offspring: 2 (high) .
Average number of offspring: 2.
Range age at sexual or reproductive maturity (female): 8 to 9 years.
Range age at sexual or reproductive maturity (male): 8 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); 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)
The chain catshark or chain dogfish (Scyliorhinus retifer) is a small, reticulated catshark that is biofluorescent. The species is common in the Northwest Atlantic, Gulf of Mexico, and Caribbean.[2] It is harmless and rarely encountered by humans.[3] It has very similar reproductive traits to the small-spotted catshark (S. canicula).[4]
The chain catshark is found in the Northwest Atlantic, Gulf of Mexico and Caribbean, ranging from George's Bank in Massachusetts, to Nicaragua and Barbados.[1] In the Mid-Atlantic Bight, the chain catshark is found along the outer continental shelf and upper slope.[2] The shark occupies depths of 36 to 750 meters (118–2,461 ft); in the northern part of its range it is mainly found between 36 and 230 meters (118–755 ft) and in the southern areas generally deeper than 460 meters (1,510 ft).[5] Due to the shark's depth distribution, it has been suggested that the shark does not perform large-scale migrations.[2]
Temperature is thought to limit the shark's distribution in northern areas, particularly during the winter. Although bands of warm water at the edge of the shelf have been observed, the temperature varies seasonally, thus limiting this non-migratory species.[2] In general, the chain catshark is found in waters with a temperature between 8.5 °C (47 °F)[5] and 14 °C (57 °F).[6]
Jaws
Upper teeth
Lower teeth
The catshark spends the daytime resting at the bottom, usually in contact with certain structures. It has been observed with large burrowing cerianthid anemone tubes and boulders.[2] The bottom rubble is thought to be used as a camouflage with the shark's spotted surface.[4] Adult sharks tend to prefer rough bottoms, creating a difficulty for trawl sampling, while the immature forms are found near smoother regions. The chain catshark has been known to feed on squid, bony fish, polychaetes and crustaceans.[1] In aquaria, they are relatively motionless, spending the day resting on the bottom, but during the night and when fed they are very active.[7]
The maximum length of this shark is 59 centimeters (1.94 ft).[6]
In the female chain catshark, follicle development has been correlated to nidamental gland size, thus, they are considered mature when they have a fully developed nidamental gland or shell gland.[4] This is marked by the glands growth to 1.8 cm (0.7 in) or more in width. Sexual maturity in the female is seen at 52 centimeters (1.71 ft) in length under normal conditions. There has been evidence however that some northern populations of the shark may mature at a smaller size, at 41 centimeters (1.35 ft). In the male catshark, testis development is correlated to clasper size, thus maturity is marked when it develops hardened claspers that are 3 cm (1.2 in) or more in length.[4][8] Males reach maturity at a length between 37 and 50 centimeters (1.21–1.64 ft).[6]
Observed mating between the species suggests biting plays an element and that mating occurs repeatedly. Behavioral observations include the male biting the female until it can get a firm grasp and subsequently wraps its body around the female for copulation.[4] After copulation, the male releases his bite and both separate.
The chain catshark prefers vertical structures for egg deposition and always deposits eggs in pairs. The interval between pairs of eggs ranges from a few minutes to 8 days.[4] Development rates average 1 mm diameter per 7.7 days although temperature has also been seen to affect follicle development.[4]
The female chain catshark is able to store sperm and lay eggs several days after initial copulation. The shark has been known to store sperm up to 843 days although, there are some circumstances of poor egg development in eggs laid later. It is suggested that this could be due to a number of factors including, senescence, low sperm viability, or water quality factors.[4]
Egg cases found in the oviduct are soft, pale yellow and translucent. They also feature two coiled tendrils, a key adaptation which allows snagging on rocks or man made structures, providing grounding and safety. When deposited, they become hardened and become dark amber with white bands.[9]
Embryos take 8–12 months to develop due to temperature variations in the environment. The catshark lays eggs in their blastodisc form. The following exhibits a typical developmental timeline (measurements are embryo length):[4]
The chain catshark is one of four elasmobranch species shown to possesses biofluorescent properties.[10] The researchers of the study examined the vision of Scyliorhinus retifer using microspectrophotometry and designed a "shark-eye" camera that yielded contrast information on areas where fluorescence is anatomically distributed on the shark. The repeated evolution of biofluorescence in elasmobranchs, coupled with a visual adaptation to detect it; and evidence that biofluorescence creates greater luminosity contrast with the surrounding background, highlights the potential importance of biofluorescence in elasmobranch behavior and biology.[10][11] The key fluorecent pigments in the chain catshark and the swell shark are a set of brominated kynurenine compounds that appear to be synthesized by the kynurenine pathway starting from 6-bromo-tryptophan.[12] The biochemical origin of 6-bromo-tryptophan in these species is not known.
The chain catshark is not currently fished for human consumption.[1][13]
The chain catshark has been described as "gorgeous",[14] and this, combined with its small size, makes it a popular cold-water aquarium fish.[7][13] It is frequently displayed and bred at public aquariums.[4][7] Research in shark behavior, including reproduction, has been done in chain catsharks kept in public aquariums or laboratories.[4][6]
The chain catshark or chain dogfish (Scyliorhinus retifer) is a small, reticulated catshark that is biofluorescent. The species is common in the Northwest Atlantic, Gulf of Mexico, and Caribbean. It is harmless and rarely encountered by humans. It has very similar reproductive traits to the small-spotted catshark (S. canicula).
