Sharks in the family Carcharhinidae
have an eyelid that moves up to
cover the eye and protect it from
physical harm. In this Caribbean
Reef Shark (Carcharhinus perezi) this
“nictating membrane” is half-closed.
The mouth is to the left.Photo courtesy
of Jeff Rotman, http://www.jeffrotman.comLeft eyes of two Common Stingarees,Trygonoptera testacea, a shallow-water stingray from Australia that has a re-
tractable eyelid. The photo on the left shows the eye condition under relatively low light levels with the pupil cover
retracted. On the right, the reflective cover is hanging down over the black pupil. The cover is thought to control the
amount of sunlight entering the eye during the day. The opening to the right of the eye is the spiracle, through which
water is drawn for breathing.Photos used with kind permission of Dave Harasti, http://www.daveharasti.com
A free-swimming, newborn Spiny
Dogfish with its yolk sack still at-
tached. Normally, shark pups use up
their yolk supply and absorb the sack
before birth, but this newborn was
probably born prematurely when its
mother was caught in a net.Photo
courtesy of Jeff Rotman, http://www.jeffrotman.comhttp://www.ebook3000.com