Dwarf Lantern Shark

The dwarf lanternshark appears to reach a maximum length of about 20 cm (7.9 in) (female). It has a long, wide, flattened head comprising a fourth to a fifth of its total length. The eyes are large, twice as long as high, with the anterior and posterior corners acute. The nares are large and preceded by poorly developed flaps of skin. There are 25–32 tooth rows in the upper jaw and 30–34 tooth rows in the lower jaw. The upper teeth of adult males have a single cusp flanked by two pairs of smaller cusplets, while the upper teeth of females are more robust and have only one pair of lateral cusplets flanking the central cusp. The lower teeth each have a single, strongly oblique cusp, and their bases are interlocked to form a continuous cutting surface. Scattered, sparse papillae are inside the mouth and on the edges of the gill arches. The five pairs of gill slits are small. The trunk is short, with two relatively closely spaced, large dorsal fins bearing grooved spines in front. The first dorsal fin originates over the trailing margins of the pectoral fins. The second dorsal fin has twice the area of the first and is larger than the pectoral or pelvic fins, and originates over the end of the pelvic fin bases. There is no anal fin. The caudal fin is low, with a moderate lower lobe and a ventral notch near the tip of the upper lobe. …

At present, the dwarf lanternshark has been reported only from a small area of the Caribbean Sea off the coasts of Colombia and Venezuela, occurring between Barranquilla and Santa Marta, near the Guajira Peninsula, and between the Los Testigos Islands and Grenada. This shark apparently inhabits the upper continental slope at a depth of 283–439 m (928–1,440 ft).

Perhaps the smallest living shark species, male dwarf lanternsharks mature at a length of 16–17.5 cm (6.3–6.9 in) and females from a length of 15.5 cm (6.1 in) with 19–20 cm (7.5–7.9 in) long pregnant individuals known. The spined pygmy shark (Squaliolus laticaudus) and the pygmy ribbontail catshark (Eridacnis radcliffei) are known to attain maturity at comparably small sizes; difficulties in assessing the reproductive maturity of sharks precludes stating one of these species as definitively smaller than the others. This species is aplacental viviparous, with the developing fetuses being sustained by a yolk sac until birth. Females bear litters of two or three young, each measuring 5.5–6.0 cm (2.2–2.4 in) long.