April Elasmobranch of the Month: Swell Shark
Swell Shark Cephaloscyllium ventriosum
Distinguishing Features The swell shark has varying degrees of colouration from yellow-light brown/tan paired with brown blotches and white spots that extend both the body and fins of the shark on the dorsal side. The spots are also present on the ventral side of the shark. Their body is stout with a small but broad snout and large oval shaped eyes (often golden in color) with a lower nictitating membrane. The swell shark has on average between 55-60 short but sharp teeth (Florida Museum. unknown) and the largest swell shark recorded was 110 cm, however they average around 90 cm in length.
Video: Discovery Channel- Shark Week
Be careful: lots of people get the swell shark and the leopard shark mixed up due to their similar features (Florida Museum. unknown) Habitat The swell shark is restricted in their range to the eastern Pacific Ocean, from California USA to the south of Mexico (Villavicencio-Garayzar et al., 2015). They can be found up to a depth of ca. 500m, but usually inhabit the euphotic zone between 5- 40 m (Villavicencio-Garayzar et al., 2015). Primarily, this species is found over algae-covered bottoms and crevices close to kelp forests.
Image Credit: Andy Murch- Big Fish Expeditions
Food Source Food sources include, bony fish, crustaceans and molluscs and as they are nocturnal, prefer to eat at night! Status The swell shark is listed as “Least Concern” by the IUCN Red List of Threatened Species. Threats Generally, this species is seldom targeted and if caught is usually due to bycatch. Gear that usually is involved in the bycatch of swell sharks include gillnets, trawls and lobster traps (Villavicencio-Garayzar et al., 2015). Fun facts: The swell shark’s name comes from its adaptation that allows the swell shark to inflate its body! It does this by gulping large quantities of seawater. The swell shark does this so that they can appear bigger to a predator or so they can wedge themselves into a small crevice to avoid predation! The swell shark belongs to one of three elasmobranch families that display biofluorescence (Gruber et al., 2016). The fluorescence exhibited between male and female swell sharks are different and cannot be seen by all animal species (Gruber et al., 2016). Due to this, scientist believe the swell shark my have biofluorescence to communicate and recognize one another or to throw off predators (Gruber et al., 2016)" References Florida Museum. unknown. Cephaloscyllium ventriosum. https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/cephaloscyllium-ventriosum (Accessed 8th April 2018) Villavicencio-Garayzar CJ, White CF, Lowe CG. 2015. Cephaloscyllium ventriosum. The IUCN Red List of Threatened Species2015. eT60227A80671800. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T60227A80671800.en (Accessed 8th April 2018)