User:Yewww/Squalus Bassi

The long-snouted African spurdog (Squalus bassi sp, nov.) is part of the Squalidae (dogfish) family of sharks which is part of the order Squaliformes. This species is a chordate and part of the phylum vertebrata. Within vertebrata it is classified as a chondrithyes, which means cartilaginous fish.

Geographic Distribution

The long-snouted African spurdog is a benthic and pelagic species that inhabits the outer shelf and the upper continental slope off the coasts of South Africa and Mozambique in the southeastern Atlantic Ocean and the Western Indian Ocean. These waters are generally around 200 meters in depth and is part of the photic zone. They are inhabitants of the neritic zone of the ocean and generally live at a depth of around 150-200 meters but can be found anywhere from the surface to depths greater than 500 meters. No research on the migratory patterns of this species of shark has been done, but other species of dogfish are highly migratory and require temperate water.

Anatomy

Squalus bassi sp, nov. has a fusiform and robust body with the greatest width at the head. It has an obtuse and elongated snout. This species has two dorsal fins and no anal fin. They have two pelvic fins that are located at the midline between the dorsal fins. They have very large eyes which contain a tapetum lucidum and a lot of rods to have effective vision in low light conditions. The long-snouted African spurdog had a dark grey to brownish grey dorsal side, with a white underbody. This countershading helps them blend into the water and be harder to see, which increases fitness. Like other species of sharks, the have placoid scales, which are overlapping and rough like sandpaper. They also have a heterocercal tail formed by asymmetrical lobes, with a larger upper lobe. Juveniles can be differentiated by having a browner dorsal side. ''Squalus bassi sp, nov. ''can be distinguished from other sharks by their large snout with a prenarial length greater than the distance between the nostrils. It can be commonly mistaken for other long-snouted species of dogfish due to a lot of similar morphological characteristics but have recently been differentiated. Squalus bassi sp, nov. lacks the black caudal bar on post ventral caudal margins, which is a characteristic of many other long-snouted species and the location of its pelvic fins (midline between dorsal fins) which varies between long-snouted species. They also have a rectangular upper caudal lobe, a concave caudal fork, and dorsal and ventral caudal tips, which differentiate them from other species. They swim with rhythmic contractions of its myomeres that create an S-shaped wave of the body which pushes against the water and forces its body forward. They require this movement to breathe as they breathe through ram ventilation. This type of respiration requires constant movement to move oxygenated water over their gills.

Diet and Eating

The long-snouted African spurdog feeds diurnally and nocturnally, detecting food by olfaction, vision, acoustics and by using their Ampullae of Lorenzini to detect electrical fields of living organisms. They are schooling fish, and school by size, which allows them to benefit from the sensory efforts of the group to locate potential pretty. While no studies have been done on this species, the spiny dogfish stomach contents was dominated by fish, squid and ctenophores (commonly known as comb jellies). This is a closely related species to the long snouted African spurdog, and they likely have similar diets. They tend to feed on squid and fish throughout their life, eating bigger individuals as they continue to grow. However, the long-snouted African Spurdog is likely an opportunistic feeder like other species of dogfish, and will also probably eat things like flatfishes, blennies, shrimps, crabs, octopods and sea cucumbers.

Reproduction

Distinguishing between male and female Squalus bassi sp, nov. is relatively simple, with the males being slightly smaller at maturity and having claspers as an intermittent sexual organ and allowing for internal fertilization. Mating practices of Squalus bassi sp, nov. has not been evaluated, but other species of dogfish mate in the fall. Males fertilize eggs by inserting their claspers into the cloaca of females to transfer sperm. Gestation lasts for around 22-24 months and these sharks are ovoviviparous and mothers give birth to live young. Females can continue to mate each year, even if gestation from the previous mating is still occurring. While in the womb, the embryo long-snouted African spurdogs develop from the yolk sacs inside their eggs. Litters range from 2-11 pups and the sex ratio of other species of dogfish sharks are 1:1 and is likely the same for the long-snouted African spurdog. Due to this long gestation and low fecundity, the long-snouted African spurdog is particularly vulnerable to population collapse.

Life Stages

At birth, females are estimated to be 24.6 cm in length and males estimated to be 25.7 cm in length. Birth occurs offshore in the fall or the winter and with a sex ration of 1:1. They remain physically immature for 10 or more years but reach sexual maturity earlier. At sexual maturity, females are around 7.5 years old and have an average size of 65.9 cm. Males reach sexual maturity at 5.5 years, and have an average size of 57.5 cm. As Squalus bassi sp, nov. continues to mature, females stay larger than males.

Bibliography


 * 1) Carlson, Amy E., et al. "The Use of Satellite Tags to Redefine Movement Patterns of Spiny Dogfish (Squalus acanthias) along the U.S. East Coast: Implications for Fisheries Management." PLoS ONE, vol. 9, no. 7, 28 July 2014. Gale Academic OneFile, link.gale.com/apps/doc/A417671858/AONE?u=mlin_b_bumml&sid=bookmark-AONE&xid=ed7fdfda. Accessed 10 Apr. 2022.
 * 2) Crow, Gerald L., et al. "Vertical distribution, diet, and reproduction of the velvet dogfish (Zameus squamulosus) in waters off Hawaii." Fishery Bulletin, vol. 116, no. 2, Apr. 2018, pp. 207+. Gale Academic OneFile, link.gale.com/apps/doc/A541400259/AONE?u=mlin_b_bumml&sid=bookmark-AONE&xid=4927f373. Accessed 10 Apr. 2022.
 * 3) Henderson, Flannery, K., & Dunne, J. (2002). Growth and Reproduction in Spiny Dogfish Squalus Acanthias L. (Elasmobranchii: Squalidae), from the West Coast of Ireland. Sarsia, 87(5), 350–361. https://doi.org/10.1080/0036482021000155805
 * 4) Stehlik, Linda Louise. "Essential fish habitat source document. Spiny dogfish, Squalus acanthias, life history and habitat characteristics." (2007).\
 * 5) Viana, S.T.d.F.L., de Carvalho, M.R. and Ebert, D.A. (2017), Squalus bassi sp. nov., a new long-snouted spurdog (Chondrichthyes: Squaliformes: Squalidae) from the Agulhas Bank. J Fish Biol, 91: 1178-1207. https://doi-org.ezproxy.bu.edu/10.1111/jfb.13448