taillight shark

Taxonomy:

Phylum– Chordata

Class– Chondrichthyles

Subclass– Elasmobranchii

Order– Squaliformes

Common Name– Dogfish Sharks

Family– Dalatiidae

Common Name– Kitefin Sharks

Genus– Euprotomicroides

Species– zantedeschia

Status: IUCN Red List DATA DEFICIENT

Average Size and Length: The first Taillight shark specimen was an immature female 6.9 inches long, the second was a mature male 1.4 feet long, the third was also a mature male 1.5 feet long and the fourth specimen was a mature female 1.7 feet long.

Current Rare Mythical Sightings: Only 4 Taillight shark specimens have been collected. The first specimen of the Taillight shark was collected by the Cape Town trawler Arum in 1963 and was initially identified as a Longnose Pygmy shark before being recognized as a previously unknown species. The genus name Euprotomicroides comes from this shark’s resemblance to the Pygmy shark. The specific description zantedeschia is derived from Zantedeschia aethiopica, a species of arum lily for which the trawler Arum was named. (Hulley, P.A. & Penrith, M.J. (1966): Euprotomicroides zantedeschia, a new genus and species of pigmy dalatiid shark from South Africa. Bulletin of Marine Science, 16 (2): 222-229.)

Teeth and Jaw: The mouth of the Taillight shark is large, containing 29 tooth rows in the upper jaw and 34 tooth rows in the lower jaw. The upper teeth are small and needle-like, while the lower teeth are large and triangular, with their bases interlocking to form a continuous cutting surface. The lips are thick and fringed, though not modified to be suctorial. The jaws are strong.

Head: The Taillight shark has a long, rounded, bulbus snout and large oval eyes.

Denticles: The body of the Taillight shark is covered by small, non-overlapping dermal denticles; each denticle has radial ridges converging to a round central pit.

Tail: The caudal fin of the Taillight shark has a strong lower lobe and a long upper lobe with a prominent notch near the tip.

Demographic, Distribution, Habitat, Environment and Range: South Atlantic. The Taillight shark is quite possibly epipelagic. The four specimens of the taillight shark were caught off South Africa in a trawl operating at a depth of 1,503–2,103 feet, off Uruguay in a trawl operating at a depth of 640–673 feet and off Chile, near Juan Fernandez Islands. These records suggest that the Taillight shark is an inhabitant of the open ocean. However, whether the known specimens were captured near the sea bottom where the trawls operated or from midwater as the nets were being retrieved is unclear.

Diet: Large jaws and teeth of the Taillight shark suggest that they challenge large prey.

Aesthetic Identification: The Taillight shark has a laterally compressed body. The body of the Taillight shark is dark brown above and black below, with light margins on the fins. Small, light-emitting or bioluminescent photophores are scattered over the body, possibly for the use of counter illumination. The Taillight shark has unusual adaptations that indicate a specialized lifestyle: its pectoral fins are paddle-like and may be used for propulsion, unlike other sharks and it has a pouch-like gland on its abdomen that emits clouds of luminescent blue fluid. On the belly in front of the cloaca is this pouch-like groove devoid of denticles and lined with a luminescent tissue formed into numerous, tightly packed yellow papillae. The entrance to the pouch is a slit lined with folds of skin. In life, the pouch emits a glowing blue fluid of unknown function.

The five pairs of gill slits are large and increase in size from the first to the last. The fifth one is wide, about twice the length of the first. The two dorsal fins are rounded and lack spines; the first is smaller than the second and located about halfway between the pectoral and pelvic fins. The pectoral fins are enlarged into rounded paddles. The pelvic fins are small and originate at the level of the second dorsal fin; the anal fin is absent.

Biology and Reproduction: The Taillight shark is likely ovoviviparous.

Behavioral Traits, Sensing and Intelligence: Based on its adaptations, the Taillight shark probably has a highly specialized lifestyle and is a daunting predator, but much more research is needed. The muscular, lobe-like pectoral fins of the Taillight shark suggest they may be used for propulsion, in a manner more similar to that of chimaeras than other sharks or at least for hovering in the water column.

One of our hypotheses about the glowing fluid; being a possible deepwater shark, living in darkness, it could be used similar to octopuses’ ink, confusing possible predators, or it could be used to attract prey or even mates. Research is unclear how or when the shark emits the fluid or even controls it. Much research is needed. Imitating the shark swimming away after the pouch emits the fluid, it would appear coming from the tail, and thus suggesting uses in defense or camouflage.

Speed: Possibly strong in propulsion.

Taillight Shark Future and Conservation: The Taillight shark is not caught significantly by any fishery, possibly due to its small size and habitat preferences. There isn’t enough data to consider at this point.

Taillight Shark Recorded Attacks on Humans: Not a threat to humans.