Table of Contents

Enchanted Learning All About Sharks!

Geologic Time Chart

Shark Glossary

ICE AGE An ice age is a time lasting thousands of years during which the Earth is very cold and largely covered by ice and glaciers.	ICHNOFOSSILS Also known as trace fossils, these are fossilized footprints, nests, dung, gastroliths, etc., but not actual body parts. Ichnofossils record the movement and behavior of animals.	ICHTHYOLOGIST Ichthyologists are scientists who study fish.
ICHTHYOSAUR Ichthyosaurs were prehistoric reptiles that lived in the sea.	IGNEOUS ROCK When molten rock cools, igneous rock is formed.	INDEX FOSSILS Index fossils are commonly found fossils that are limited in time span. They help in dating other fossils. For example: trilobites were common during the Paleozoic, but not found before the Permian period, and ammonites were common during the Mesozoic Era, but not found after the Cretaceous period.

INSECTS Insects have exoskeletons and six legs. They evolved during the Silurian Period, 438 to 408 mya, long before dinosaurs or whales existed.

INTERSPECIFIC COMPETITION Interspecific competition is competition between two different species of organisms (competing for food, territory, etc.).

INTRASPECIFIC COMPETITION Intraspecific competition is competition among members of a species (competing for food, mates, territory, etc.).

INVERTEBRATE Invertebrates are animals without a backbone. Some invertebrates include protozoans, arthropods (insects, arachnids, crustaceans, etc.), worms, jellyfish, sponges, mollusks (like cephalopods [octopus], gastropods, bivalves [clams, oysters, scallops]), and many others.

ISOTOPE An isotope of an element is another form of the same element, that has a different number of neutrons in the nucleus (giving it a different atomic weight).

IZAK CATSHARK The Izak catshark, Holohalaelurus regani, is also known as the Izak shark and the shy eye shark. This shark hides its eyes with is tail when it is caught. It has dark brown skin above, with lighter dots and lines. The belly is much lighter. The Izak shark grows to be up to 2 feet (61 cm) long. It has an anal fin, 5 gill slits, 2 dorsal fins, no fin spines, mouth behind the eyes, slit-like pupils, and nictitating eyelids. It is oviparous, laying eggs (3.5 by 1.5 cm) that were internally fertilized. The Izak catshark was named by Gilchrist in 1922. Classification: Order Carcharhiniformes (ground sharks), Family Scyliorhinidae (catsharks), Genus Holohalaelurus, Species H. regani.

JURASSIC PERIOD Birds evolved and many dinosaurs flourished during the Jurassic period, 208-146 million years ago.

JUVENILE A juvenile animal is one that is weaned from its mother (no longer drinking mother's milk) but is not yet sexually mature.

KERATIN Keratin is the stiff substance that baleen, hooves, hair, horns, and fingernails are made of.

KIDNEY-HEADED SHARK Kidney-headed sharks Sphyrna lewini are also known as Scalloped Hammerheads. The front of the head of this shark is flattened, scalloped and wide, forming a structure called a cephalofoil. This oddly-shaped head helps the shark swim, making the shark more hydrodynamic. The eyes are at the tip and slightly below the head. The head is also dense with sensory receptors. Kidney-headed sharks grow to be about 10-13 ft (3-4 m) long. They swim in warm temperate and tropical waters. They eat bony fish, and cephalopods. Pups are born live in litters of 15-30; they are 17-22 inches (43-55 cm) long at birth. Classification: Order Carcharhiniformes

KILLER WHALE Killer whales, or orcas, (Orcinus orca) are toothed whales, powerful carnivores that eat fish, squid, and marine mammals. They grow to be about 27 feet long (8 m) and weigh about 8,000 - 12,000 pounds (3600-5400 kg).

KRILL Krill are tiny animals, euphasiids, that float in the oceans. They are shrimp-like crustaceans that are found in vast amounts in the cold waters of the Arctic and Antarctic Oceans. Baleen whales eat krill that they sieve through their baleen. Blue whales can eat about 4 tons of krill each day.

K-T EXTINCTION The K-T extinction was the mass extinction that occurred 65 million years ago, at the boundary of the Cretaceous and Tertiary periods.

Zoom Sharks Shark Glossary

Enchanted Learning^®
Over 35,000 Web Pages
Sample Pages for Prospective Subscribers, or click below

Click to read our Privacy Policy

E-mail