Rays are broad, flattened, cartilaginous fishes which have gill slits
on the undersides, behind the mouth, rather than on the sides as they are in sharks,
to whom they are closely related.
Rays have slender tails and very well developed
pectoral fins. Most rays live on the bottom, but they can swim remarkably well
by undulating beats of the pectoral fins.
The "true rays" lay eggs, each enclosed in a rectangular horny capsule.
In most other rays, the embryos develop inside the oviducts, for live birth.
Rays breath in through "spiracles" on the side of the head behind the eyes,
with the water exhaled through the gill slits underneath.
Rajiformes consists of approximately 340 species of rays
which can be classified into seven major families: