Category Zoology

Life under a Microscope

If you picked up a cupful of seawater, you might see a few creatures. But, if you looked at the same cup of water under a microscope, you would see hundreds or thousands of little creatures!

Some of the creatures are tiny animals. Some are the young of bigger animals. You’d also see living things like plants. Huge masses of these animals and plants drift in the ocean. Together they are called plankton. Plankton is food for a great many sea creatures, from shrimp to whales.

In a cupful of pond water you would see different creatures. One looks like the bottom of a shoe. It’s called a paramecium and has no head and no legs. It doesn’t have eyes or a mouth either. Its body is covered with rows of little hairs called cilia that it uses like oars to move through the water.

Another creature looks like a funnel with a long tube. It creates a little whirlpool around the top of the funnel to draw food into its body. This creature is called a vorticella.

Another creature found in ponds is an amoeba. It looks like a blob of grey jelly, and it changes shape every time it moves.

Even though these creatures are microscopic, they are an important part of the world of animals. Without them, many other animals would go hungry.

An Underwater Garden

When is a garden made of animals? When it is made by tiny animals called corals! Beautiful “gardens” cover the seafloor in warm, shallow parts of the ocean.

Thousands of corals live together in colonies. Coral colonies are made from limestone. The limestone forms a home where the corals live. Coral colonies can be shaped like fans, beach balls, candlesticks, and other shapes. They can be red, pink, orange, blue, green, or purple.

Each individual coral is called a polyp. Corals are actually relatives of jellyfish. Like jellyfish, coral polyps send out special feelers that sting tiny ocean creatures. The polyps eat these creatures.

Together, many corals form a coral reef. Coral reefs are the richest parts of the ocean. They provide a home for countless fish and other ocean animals. Many colourful creatures live and hide in the crevices and tunnels created by coral.

A Real Live sea Monster

It has eight long, rubbery legs and two huge, staring eyes. The octopus is so scary-looking to some people that it is sometimes called the devilfish. But octopuses rarely attack people. They use their strong arms, called tentacles, to catch shellfish and swim away from danger. Some kinds also have a poisonous bite.

There are about 50 kinds of octopuses. Most of them are about the size of a kitten. But some measure 8.5 metres from arm tip to arm tip.

The octopus is a mollusc. It has no bones, but a tough covering called a mantle protects its body and gives it shape. Rows of round muscles under each arm act as suction cups. These suckers can hold onto an object even if the octopus’s arm is cut off!

When an octopus is frightened it produces a cloud of inky liquid. The inky liquid makes it hard for an enemy to see or smell the octopus. That’s how the octopus gets away.

Magnificent Molluscs

Imagine having a soft body, with no backbone to hold you up and only one foot to help you move. That’s what clams are like. Clams belong to a group of animals called molluscs. Molluscs have soft bodies with no skeleton. Some molluscs, such as snails, clams, oysters, and scallops, have outer shells for protection. Slugs, octopuses, and squids are molluscs that have no outer shells.

Molluscs live in most parts of the world. Land snails and slugs live on land. Octopuses, squids, and oysters, live in the seas and oceans. Some clams and snails live in rivers, lakes, ponds, and streams.

Wherever molluscs live, they must keep their bodies moist to stay alive. That’s why slugs and some land snails can be found under damp leaves or in the soil.

Some molluscs live between two shells that can open and close like a book. These animals are called bivalves. Clams, cockles, mussels, oysters, and scallops are bivalves. Bivalves usually keep their shells open just a little so that food can drift in. They eat tiny plants that float by in the water.

Fish, mammals, and birds all have something in common – a backbone. They belong to a group of animals called vertebrates. But some of the most fantastic creatures in the sea are animals that have no backbones. They belong to a group of animals called invertebrates.

Some invertebrates are huge, like the giant squid. Others are so tiny that you need a microscope to see them.

Some invertebrates, like crabs, clams, and sea spiders, have hard shells. The shells protect their soft bodies. Other invertebrates, like starfish or sea urchins, have spikes to protect them. Jellyfish and other invertebrates are soft all over. Jellyfish look like see-through blobs. They float gracefully through the sea. Their stinging tentacles are their protection!

Whether they have shells, spines, or stinging tentacles, invertebrates are some of the most interesting creatures in the sea!

There are thousands of kinds of fish. If you tried to choose the most fantastic fish, you’d have a hard time.

The mudskipper has a head like a frog and a body like a fish. It often crawls onto land. It can jump up and catch flying insects in its mouth.

The archerfish shoots its food down with water. The archerfish swims at the top of the water until a beetle comes buzzing past. Then the fish shoots a stream of water from its mouth. The water hits the beetle with such force that it falls down into the water. The archerfish gobbles it up.

The elephant-nose mormyrid is well named. Its long nose looks Re an elephant’s trunk.

Leafy sea dragons are odd-looking, too. Their spiky fins make them look like pieces of seaweed.

A gulper eel looks just like a huge mouth with a long, tapering tail attached to it. It can open its mouth wide enough to swallow a fish much larger than itself.

A flounder has both eyes on one side of its body. And let’s not forget the glass catfish. You can see its insides.

These are just a few of the strange fish that live in the world. Which do you think is the most fantastic?

Many people fear sharks. But most sharks are harmless. In fact, the biggest sharks of all, the whale shark and the basking shark, eat only small fish and plankton.

Great white sharks and tiger sharks are more dangerous. They eat almost anything, from rubbish to big fish, seals, and sea turtles. Another dangerous shark is the hammerhead. It has a wide head shaped like a hammer, with an eye at each end. These sharks have been known to attack people.

Sharks are different from most other fish in several ways. Their skeletons are made of a tough, rubbery substance called cartilage, not bone. And the scales of sharks are not smooth like those of other fish. They are like millions of tiny, rough teeth that protect the animal. Shark’s gills are open, not covered like those of other fish. They look like slits on each side of the shark’s body. Sharks don’t have an air bladder like other fish, either. Instead, their livers are filled with oil, which is lighter than water. Also, gulping air helps them stay afloat. Even so, if a shark stops swimming, it will sink!

Picture Credit : Google

Grunt, croak, snore, squeak, click, and roar – the ocean is a noisy place! Many of these sounds are made by fish.

Some fish are named after the sound they make. One kind of fish rubs its teeth together to make a grunting noise. That fish is called a grunt. Another fish is called a croaker. Can you guess why?

Pollock, haddock, angelfish, grouper, and many other fish also make grunting noises. They grunt by vibrating some of the muscles against the swim bladder, an air-filled sac inside their bodies. The seahorse makes a clicking noise by hitting a bone on its head against a bone on its back.

Sharks sometimes make a roaring sound. But they aren’t really roaring – they’re burping! Many, sharks swallow air to help them stay close to the surface. When they want to dive deeper in the water, they have to burp up the air. The burp sounds like a roar.

Scientists study fish sounds to see if they mean anything. They say that many sounds seem to be made by male fish calling to female fish. Others are made by fish getting ready to fight.

Picture Credit : Google

Most fish eggs never hatch. Many wash ashore and dry up, and many are eaten by other fish. So, in the dangerous world of the sea, some male fish give their eggs extra care.

A male smallmouth black bass cares for its young even before they’re hatched. He makes a wide, saucer-shaped hole in the sand where the female bass lays her eggs. The eggs are sticky. They stick to the sand and do not float away.

After the female lays the eggs, the male guards them all by himself. He also fans them with his tail. This keeps the water around the eggs fresh and helps them hatch.

When the young hatch, the male watches over them as they learn to swim. He fights anything that comes near. Later, the male guards them while they find food.

A male jawfish keeps eggs in his mouth. After they hatch, he holds the young in his mouth until they’re big enough to live on their own. Then he spits them out into the water, and away they swim.

If an animal or plant lives in the water, chances are it is food for a hungry fish.

In the ocean, most fish eat only other fish. Large ocean fish, such as cod, hake, tarpon, and tuna, dine on smaller fish – herrings, sardines, and anchovies. Of course, sometimes the bigger fish are food in turn for sharks!

In rivers and lakes, fish eat fish, too. But some add other tasty things to their diet. Trout jump out of the water to snap at flying insects. Big hungry bass, pike, and bowfins gobble up frogs, baby ducks, and even baby muskrats.

Some kinds of fish eat plants. Carp and suckermouth catfish swim along the bottom of rivers and ponds. With tiny teeth, they chew up bits of plants that grow in the mud.

Some fish eat plants, animals, and other organisms. Parrotfish eat plant-like organisms called algae and tiny worms that live in coral. The ocean sunfish eats small shrimp, baby fish, jellyfish, and algae.

And the largest fish of all eat the smallest food. Whale sharks, giant manta rays, and basking sharks eat only plankton.

Picture Credit : Google