Featured Species: Bramble Shark (Echinorhinus brucus)

This week’s featured species comes to us from the inky depths of the ocean. The Bramble Shark (Echinorhinus brucus) is one of two species in the family Echinorhinidae; the second member being the Prickly Shark (Echinorhinus cookei) (Tricas, et al., 1997). The bramble shark spends its life near the ocean floor at depths between 650 – 1970 feet (200 – 600 m) but is occasionally observed nearshore. This large bodied shark has a broad, flatten head and snout with large eyes (Ebert, Fowler, & Dando, 2015). These sharks are uniformly brown or brown-grey across their bodies, but are speckled by large, knobbly dermal denticles (Parker, 2008).

Echinorhinidae_-_Echinorhinus_brucus
Hectonichus (Photographer). (2015). Echinorhinus brucus, mounted specimen, on display at the Museo di Storia naturale di Pisa [Digital Image]. Retrieved from https://commons.wikimedia.org/

Much of the bramble shark’s life is still a mystery to science. Deep water species are notoriously difficult to study. From the specimens we have been able to study, we know the bramble shark has a variety of prey items in its diet, including bony fishes, invertebrates, and other chondrichthyans (Ebert, Fowler, & Dando, 2015). To go along with the ranging prey items, the bramble shark has a mouth full of formidable teeth. The teeth in the upper and lower jaws exhibit the same morphology (Klimley, 2013). They have a single large cusp flanked by three smaller cusplets on either side. Juvenile bramble sharks lack these cusplets, and develop them as they reach sexual maturity (Compagno,1984).

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Left: Robertson, D. R. (Photographer). (2016). Echinorhinus brucus upper jaw [Digital Image]. Retrieved from https://commons.wikimedia.org/ Right: Robertson, D. R. (Photographer). (2016). Echinorhinus brucus lower jaw [Digital Image]. Retrieved from https://commons.wikimedia.org/

Bramble sharks are so named because their skin resembles the prickly bramble shrub. All sharks have scales called placoid scales or dermal denticles. These scales have the same composition as their teeth; in fact, dermal denticle actually means “tooth-like scale” (Parker, 2008). Depending on the species, dermal denticles can serve a variety of functions, from stealth, to hydrodynamics, to protection (Parker, 2008). The dermal denticles of the bramble can be as large as shirt button and each have a sharp, curved thorn in the center (Ramachandran, Ayoob, & Koya, 2014). It is possible that these thorny denticles offer the bramble shark defense or protection (Parker, 2008).

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Fig. 5. (a) Distribution of dermal denticles (~5mm dia) along with Lateral line; (b) Dorsal and lateral view of larger dermal denticles; (c) distribution of smaller dermal denticles indicated by smaller black arrow and it grown on the base of bigger dermal denticle indicated by larger black arrow; (d) individual smaller dermal denticle (Ramachandran, Ayoob, & Koya, 2014).

 

Currently, the bramble shark is considered Data Deficient by the International Union for Conservation of Nature (IUCN). The reason for this classification is because so little is known about this species, including life history and current population trends (Paul, 2003). It is likely that this species is slow growing, is late to maturity, and has a low productivity rate (Paul, 2003). The greatest potential threat to this species is bycatch by commercial deep water fisheries. This species is too rare and too sporadic within its habitat to be directly targeted by commercial fisheries; however, it is sometimes caught accidentally by deep water trawlers. The bramble shark is a likely candidate for a threatened species category due to its life history characteristics, its rarity, and the potential threat from fisheries (Paul, 2003).

Approximately-250-cm-female-bramble-shark-Echinorhinus-brucus-Bonnaterre-1788-caught
Fig. 2: Approximately 250 cm female bramble shark, Echinorhinus brucus (Bonnaterre, 1788), caught off Elba Island, Italy, around 1985 (De Maddalena, & Zuffa, 2003)

Shark Stats

Authority: Bonnaterre, 1788

Family: Echinorhinidae; 2 species

Length: Up to 10 feet (3.1 m)

Weight: Maximum recorded weight of 440 lbs (200 kg)

Habitat: Benthic dweller; found in temperate and tropical continental insular shelves and upper slopes

Depth: Occasionally spotted inshore; however, typically found between 650 – 1970 feet (200 – 600 m)

Reproduction: Ovoviviparous

Gestation: Unknown

Litter Range: 15 – 25 pups

Home Range: Atlantic, Mediterranean, and Indo-West Pacific Oceans

Diet: Bony fish, small chondrichthyans, invertebrates

IUCN Status: Data Deficient

(Castro, 2010; Ebert, Fowler, & Dando, 2015)

Thanks so much for checking out the Bramble Shark! If you missed last week’s featured species, please be sure to check out the sleek and beautiful Blacktip Reef Shark! If there is a species of elasmobranch you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species. So connect with me on Instagram and Facebook for even more elasmo fun!

The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!

Conservation legislation needs public support in order to become law and help protect the environment and wildlife. Tell your representatives that you care about environmental and wildlife conservation.  It only takes a moment to make a change that will last a lifetime. Until next time finactics!

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Featured Image Source

Iglésias, & Mollen (Authors). (2018). The stuffed voucher ERB1080 of a Bramble shark 175 cm long (top and bottom right), trawled on the Galloper Bank (Suffolk, United Kingdom) in the southern North Sea on Jan. 15th, 1893. Detail of dermal denticles (bottom left) [Digital Image]. Retrieved from https://www.researchgate.net/

Literature Cited

Compagno, L. J. (1984). Sharks of the world: an annotated and illustrated catalogue of shark species known to date (No. QL 638.9. C65).

Castro, J. I. (2010). The sharks of north America. Oxford University Press.

De Maddalena, A., & Zuffa, M. (2003). A gravid female bramble shark, Echinorhinus brucus (Bonnaterre, 1788), caught off Elba Island (Italy, northern Tyrrhenian Sea). In Annales, Ser. Hist. Nat (Vol. 13, No. 2, pp. 167-172).

Ebert, D. A., Fowler, S. L., & Dando, M. (2015). Sharks of the world: a fully illustrated guide. Wild Nature Press.

Iglésias, S. P., & Mollen, F. H. (2018, November). Cold case: The early disappearance of the Bramble shark (Echinorhinus brucus) in European and adjacent waters. Oceans Past News No. 10. Retrieved from https://www.researchgate.net/publication/329275494_Cold_case_The_early_disappearance_of_the_Bramble_shark_Echinorhinus_brucus_in_European_and_adjacent_waters

Parker, S. (2008). The encyclopedia of sharks (2nd ed.). Buffalo, NY: Firefly Books Ltd.

Paul, L. (2003). Echinorhinus brucusThe IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/species/41801/10563978

Ramachandran, S., Ayoob, A. E., & Koya, P. P. (2014). A new distributional record of bramble shark Echinorhinus brucus (Bonnaterre, 1788) from the seamount of Lakshadweep Islands with description on skeletal rings. J. Mar. Biol. As. India55(2), 5-11.

Tricas, T. C., Deacon, K., Last, P., McCosker, J. E., Walker, T. I., & Taylor, L. (1997). The Nature Company Guides: Sharks and Rays. (L. Taylor, Ed.). Hong Kong: The Nature Company, Time Life Books.

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