THURSDAY, APRIL 14, 2005
What is the Difference Between Skates and Rays?
By NC Auarium
NC Aquarium
From 16 inches to 22 feet, Rays in North Carolina can vary greatly
NC - Rays and skates are similar species that are closely related to sharks. Collectively, they are known as batoids. Like sharks, their skeletons are made of cartilage instead of bones.
Cartilaginous fish belong to the class of fishes known as Chondrichthyes.
Most rays are kite-shaped with streamlined tails that may have one or more poisonous barbs or spines. In contrast, skate tails are fleshier and heavier, and have small fins. In general, skates commonly found in North American waters have elongated noses.
Size is another way to differentiate rays from their skate cousins. Rays can grow to tremendously large sizes. For example, the manta ray (Manta birostris) can reach a width of 22 feet, weighing several tons. The five species of skates commonly found in North Carolina waters range in size from 16 inches to 5 feet in length.
Rays and skates use different mechanisms to defend themselves, too. The stinging spine on the ray’s tail is an effective weapon against predators. The edges of the spine are serrated so that once driven into a victim it is very difficult to remove without creating more damage. A thin skin covers the entire structure, and when ruptured, venom is released into the victim. Since skates do not have stinging spines, they rely on large thorns on their backs and tails to deter predators.
In all, there are seven main families of rays in the Order Myliobatiformes, including stingrays, butterfly rays, devil rays, eagle rays, river rays, round stingrays and six-gill rays. Some of the individual species common off the North Carolina coast are the smooth butterfly ray (Gymnura micura), the spotted eagle ray (Aetobatus narinari), the cownose ray (Rhinoptera bonasus) and the southern stingray (Dasyatis americana).
There is only one family of skates, the family Rajidae. Skates common to North Carolina include the clearnose skate (Raja eglanteria), the winter skate (Raja ocellata), the little skate (Raja erinacea), and the barndoor skate (Raja laevis).
Condensed from the NC Aquarium website located at: http://www.aquariums.state.nc.us/ata/rays.htm
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