SHAPE OF BODY:
- Sharks typically have an elongate fusiform body (rounded and tapering at both ends). This body shape reduces drag and requires a minimum of energy to swim.
- Most bottom dwelling sharks, like the angelshark, have flattened bodies that let them
hide in the sand on the ocean bed. These slower-swimming animals usually hide on the ocean floor and burst out of the sand to surprise their prey.
- Batoids are flattened, with ventral mouth and gill openings.
SHAPE OF TAIL:
- The fast-swimming predators like the great white, mako, tiger, and hammerhead have tails with lobes that are almost the same size. Slower swimming sharks have tails that are more asymmetrical. The thresher sharks have tails whose top lobe are up to half the body length.
- The biggest shark is the whale shark, which can grow up to 47 feet long.
- The smallest shark is the spined pygmy shark, which, when fully-grown, is only 7-8 inches long.
- The largest batoid is the manta ray, with widths of over 22 feet.
- Most sharks are about the same size as people, 5-7 feet long. Half of the 350 shark species are under 39 inches long.
- Sharks and batoids are generally drably countershaded. Countershading is a type of camouflage in which the dorsal side is darker than the ventral side. The dark top of a coutershaded animal blends in with the dark ocean depths when viewed from above. The light ventral side blends in with the lighter surface of the sea when viewed from below. The result is that predators or prey do not see a contrast between the countershaded animal and the environment.
- Some coastal benthic sharks and batoids are camouflaged to blend in with the bottom. Most stripes and other markings are juvenile colors which disappear with age, as in the case of tiger sharks. Other species, such as whale sharks, wobbegongs, and zebra sharks, keep the markings throughout their lives.
- Fins are rigid, supported by cartilaginous rods.
- Sharks have five different fins:
- Paired pectoral fins lift the shark as it swims.
- Paired pelvic fins stabilize the shark.
- One or two dorsal fins also stabalize the shark. In some species, dorsal fins have spines.
- A single anal fin provides stability in species where it is present; not all sharks have an anal fin.
- The caudal fin propels the shark.
- The different families of batoids show various amounts of fin fusion and reduction. In particular, the greatly expanded pectoral fins are fused to the sides of the head, and the anal fin is absent. Stingrays have a barbed, venomous spine on a whiplike tail.