Swimming along in our rivers, lakes, streams, and oceans are some of God's most amazing creations:
fish. These beautiful animals
are mesmerizing to watch as they glide and turn in the waters of the earth. With bodies and
organs perfectly fit for aquatic life, fish have an anatomy that is a marvel to behold.
Fins are usually the most distinctive feature of the fish. Fish use them to maintain their
position, move and steer, and come to a stop. Fins make for more efficient movement in the water
than legs or arms. Fish fins have different names depending on their location on a fish's body and
they have unique uses. The caudal fin, which is the fish's tail fin, is the main fin used to move
the fish forward. The paired lobes of the fin help a fish to steer, stop, and hover in the water.
The dorsal fins, found along the top of the fish, keep the fish stable so that it doesn't roll over,
and they assist with sharp turns. A fish's anal fin, near the back of the fish along the bottom,
provides stability for the fish so it doesn't overturn in the water. The pectoral fins,
which have paired chest fins, provide the fish with the means to move directionally including
up and down or side to side. Some species, such as flying fish, use their extra-large pectoral fins
for jumping or gliding over the water's surface. Pectoral fins are often pulled close against the
fish's body when swimming quickly. Fish scales are the small protective plates that grow out of
the fish's skin and cover a fish's body. Most fish have scales but not all do. Catfish and electric
eels do not have any scales. Scales can be beautiful and shimmery. Some of the most colorful
freshwater fish, such as brook trout and rainbow trout, have scales that are vibrant with color.
If you have ever tried to pick up a fish, you know that it feels slippery.
Fish scales have a coating of slime over them to protect them from parasites that live in
the water. The slime also helps the fish glide through the water more easily. Interestingly,
scales form rings as they grow similar to the way turtle's scoots form and the way
tree trunks grow. This means you can count growth rings of scales to get an idea of the fish's age.
Fish use their mouths for eating, breathing, as well as housekeeping as they clean their habitats.
Some fish even use their mouths to carry their eggs or their young.
Some fish, such as chain pickerel and gar, have obvious teeth. Other fish,
such as catfish and striped bass, have teeth that are not easy to see. Depending on how a fish hunts
prey, its mouth can be downward-facing, upward-facing, or forward-facing. Fish
species such as bass have upward-facing mouths because they creep up on their prey from below.
Have you ever seen a fish blink? They are not able to do so because they do not have eyelids to close
their eyes. To see more clearly underwater, fish have a protective film over their eyes
instead of eyelids. Some species, such as walleye, are much better than others at seeing in the dark.
The depth of a fish's habitat can affect its perception of color.
Less light is available at greater depths, making it difficult for deep-sea fish to see
color. These fish have adapted to the depths in many ways. Some have very large eyes, while others
are able to feel slight movements in the water by the changes in pressure. One fascinating fish
is the anglerfish, which has a fishing pole atop its head with a bioluminescent lure that attracts
its prey. Fish have a pair of nostrils called nares that are used specifically for smelling,
not breathing. Fish use their nares to sense nearby predators, find mates, and even migrate.
Salmon and trout are believed to locate their spawning grounds in part by recalling the smell of
where they hatched years earlier. Eels and catfish also have a very well-developed sense of smell.
The gills of a fish are what allows it to breathe. When a fish breathes, it pulls a mouthful of water
into its gill cavity. It then pulls the side of its throat together, which forces the water
through the gill openings, passing water over the gills to the outside of the fish.
The gills have unique feathery parts that filter out the dissolved oxygen in the water,
which is then absorbed into the blood vessels. The fish's heart then pumps the blood to carry
the oxygen throughout the body. Found in many different varieties all over the world,
fish have been created in beautiful and amazing ways.