Sharpnose sevengill shark

[munnaf141579]

The first 3 or 4 teeth in the upper jaw are narrow with a hook-shaped cusp and small lateral cusps. The posterior teeth have one or two small cusps. The teeth in the lower jaw are broad and comb-shaped, with the exception of a small symmetrical tooth located at the symphysis. There are 9 to 11 teeth on each side of the upper jaw and 5 teeth on each side of the symphysial tooth in the lower jaw. (Last and Stevens 2009, Braccini 2008)

Denticles
The dermal denticles closely overlap. Each denticle is longer than wide with a larger median tooth followed by a pair of smaller lateral teeth. The median ridge is distinct. The denticles are very fine and transparent, allowing skin pigmentation to be visible. The denticles along the upper edge of the caudal fin are ovoid and lack marginal teeth. Three longitudinal ridges are present, forming a poorly defined crest.

Sharpnose sevengill shark dentition. Photos (clockwise from top) © Cathleen mexico email list Bester / Florida Program for Shark Research, George Burgess, Bigelow Schroeder (1948)
Sharpnose sevengill shark dentition. Photos (clockwise from top) © Cathleen Bester / Florida Program for Shark Research, George Burgess, Bigelow & Schroeder (1948)
Size, age and growth



Being the smallest hexanchoid shark, it only grows to a maximum length of 1.37 m (4.5 ft) in total length for males and 1.40 m (4.6 ft) in total length for females. However, this species is more commonly observed at lengths of 0.6–1.2 m (2–4 ft). Males reach maturity at 0.75–0.85 m (2.4–2.8 ft) in total length and females reach maturity at slightly larger sizes of 0.9–1.0 m (3.0–3.3 ft) in total length. Biologists have observed mucus formation on the tips of the hooks in mature and subadult males. This is thought to indicate the onset of maturity and perhaps sexual activity. (White et. al 2006).