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Glossary
Ampullae of Lorenzini
These are small pits that cover large areas of skin near the mouth and nose on the shark's snout. They are natural electrical sensors which, at close range, can detect the weak electrical fields generated by all animals.
Benthic
Living on or near the sea bottom
Camouflage
An animal's disguise, usually through color, that enables it to blend in with its surroundings.
Carnivore
An animal that eats only meat. All sharks are carnivores.
Cartilage
A tough, white, flexible material that is mostly made from protein. A shark's skeleton is made of cartilage.
Countershading
This is a form of protective coloration in which animals are darker on their upper (dorsal) surface than on their lower (ventral) surface. Many sharks, especially those that live near the surface, are a a dark color on their backs and a lighter color on their bellies. The countershading camouflages them from two directions -- looking up at them against the surface, and looking down at them against the sea floor.
Crepuscular
An animal that is active at dawn and at dusk.
Dermal denticles
Shark skin is covered by a layer of small tooth-like structures called dermal denticles. As the shark grows, the denticles are shed and replaced by slightly larger ones. The layer of dermal denticles creates a rough surface that is sometimes compared to sandpaper. Untanned shark skin, called shagreen, is used to sand and polish furniture.
Ectothermic
Having an internal body temperature that is dependent on the surrounding temperature. Most fishes, amphibians, and reptiles are ectothermic.
Gill slits
These are the slit-like openings behind a shark's head. Most sharks have five pairs of gill slits, but some have six or seven pairs. As a shark breathes, oxygen-rich water enters its mouth. The water passes over the gills and respiration takes place: oxygen in the water is exchanged for carbon dioxide in the blood. The now oxygen-depleted water exits through the gill slits.
Ichthyologist
A scientist who studies fishes.
Kelp forests
Kelp forests are formed by giant kelp that grow off the coast of California. The kelp forests provide food and shelter to a wide variety of marine animals, including sharks.
Lateral line
The lateral line is a network of sensory hair cell clusters (neuromasts) and small water-filled canals that lie immediately beneath the skin on a shark's head and extend along the sides of its body. This network is sensitive to external motion, and helps the shark detect prey and potential predators.
Mermaid's purse[Mermaid's Purse, photo © Mark Conlin]
A name sometimes given to the egg cases of sharks, such as the swell shark. The egg case is shaped like a piece of kelp with a drawstring. One baby shark grows inside it. (Photo of swell shark egg case, Mark Conlin)
Nictitating membrane
A thin, tough membrane, or inner eyelid present in the eyes of many sharks. It can be drawn across the eye to protect if it from damage.
Nocturnal
Active at night and inactive during the day.
Oviparous
Laying eggs instead of giving birth to live young. Some sharks are oviparous.
Ovoviviparous
Giving birth to live young which have developed from eggs that hatched within the mother's body. Some sharks are ovoviviparous.
Pectoral fins
Paired fins, located just behind or below the gill slits, and used for lift and movement control.
Pelagic
Of the open sea; not associated with the ocean bottom.
Predator
An animal that hunts, kills, and eats other animals. A shark is a well-adapted predator.
Shagreen
Untanned shark hide used as sandpaper for sanding and polishing furniture.
Viviparous
Giving birth to live young which have developed inside the mother by means of a plancenta and umbilical cord. Some sharks, such as the gray smoothhound are viviparous.

Shark School | Kids' Habitat

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