Science Worksheet #1

Fish Facts

In the following discussion of fish, key words have been left out.  Use the word list provided at the end to fill in the blanks.

Fish are found in almost all of the waters of the world.  They are descendants of animals that lived 400 million years ago.  Fish with jaws are divided into two major groups based on their skeletal material.  Those with cartilage are called the ______________ fishes.  Included in this group are _____________, _____________ and ____________.  These fish occur most commonly in salt water in ______, __________ and __________.  The second major group are fish with calcified skeletons.  They are called the ___________ fishes.  In addition to saltwater habitats, they are also common in freshwater ___________, _____________ and __________. 

Fish do not have legs.  They move by _______ power.  They generally have two sets of paired fins; that is, one of each pair on either side of the body.  The paired fins located highest behind the operculum are the ________ fins.  The lower fins are the _________ fins.  Most fish use these fins for steering and braking.  Some, like parrotfish and wrasses, use pectoral fins for propulsion.  Fish have three unpaired fins.   The ________ fin runs down the middle of the back and the __________ fin is found underneath near the tail.  On most fish these fins just act as stabilizers; but some fish, such as the triggerfish, swim by moving the dorsal and anal fins in a sine-wave(~) pattern.  Most fish, however, use their tail or ___________ fin for power. 

Many fish, especially the fast-swimming ones, are fusiform or ______________.  But some, such as the skates and rays, are __________ from top to bottom.  These animals are adapted to live on the bottom.  Many fish have a _____________ ___________ body that is flattened from side to side.  This shape is good for maneuvering in and out of cracks in a coral reef or thick vegetation.

Most fish catch prey or graze on algae using ________.  Many fish with up-pointing mouths feed on organisms near the water's ___________.  Bottom dwellers that feed on animals living on the bottom often have sensitive "whiskers" or ___________ located on their chin to help find food.  _______ and nurse sharks have these.   Many fast-swimming fish, like the ____________, chase and catch their food, which often includes other fish.  ___________ maneuver slowly around the reef, picking at animals or _________ with their small mouths.  Some large fish like they ______ ______ don't use teeth for feeding.  Instead, they _______ small animals from the water using modified gill rakers.

The outside of most bony fish is covered with waterproof _________.  Members of the shark family do not have these.  Instead, their skin is covered with ___________ _________, or "skin teeth."  Fish get their _________ from water rather than from air.  Water flows in the ______ and over the _______where gases are exchanged with the water.  Some fish like tuna and tiger sharks must swim constantly to force water over their gills or they will suffocate.  Others like the flounder and nurse shark can pump water over their gills and are able to rest on the bottom.  Bony fish have a gill cover or _________; sharks have ________  _________.

Word List

Each answer is used only one time.  Students may use a dictionary if needed.

Reprinted courtesy of the National Aquarium in Baltimore