Shark Colors 55may or may not be countershaded. Regardless, their backs, instead of being
a solid dark color, are a mottled gray or brown, often arranged as lighter re-
gions between dark saddles. In some sharks, such as triakid Leopard Sharks
and scyliorhinid shysharks, the saddles and blotches wrap around almost
the entire body before grading to a lighter belly. Such blotchy coloration
is similar to that of benthic (bottom-living) bony fishes such as scorpion-
fishes, flatfishes, and sculpins. This color pattern most likely makes the
animals blend into the mottled bottom against which they are seen from
above.
Skates are generally countershaded, but their white bellies are almost
always pressed against the bottom, unseen. In some skates, a pair of dis-
tinctive round bull’s-eyes decorate the exposed top side; among these are
the Eyespot Skate, Atlantoraja cyclophora; the Big Skate, Raja binoculata; the
Starry Skate, R. stellulata; and the Longnose Skate, R. rhina. (See also the
description of Epaulette Sharks in the next question.) How these “eyespots”
function is a mystery. In many animals (toads, butterflyfishes, pufferfishes,
Oscar cichlids, moths), eyespots on backs, fins, and wings are thought to
startle or perhaps fool predators into thinking they are encountering a
much larger animal. Alternatively, eyespots may invite an attack, deflecting
it away from more vulnerable body areas, such as the head. Whether skate
coloration serves a similar function is unknown.
Deviations from countershading in open-water sharks usually function
to make a small part of the shark visible when first detected. These colored
body parts probably separate one species from another, helping sharks tell
A Big Skate, the largest skate in
North American waters. The round
“bull’s eyes” on the upper surface
of the pectoral fins occur on many
skates, but their function remains a
mystery. Photo from Wikimedia Commons,
http://www.afsc.noaa.gov/race/media/photo_gallery/
fish_files/Big_skate.htm