characteristics of crayfish~~

Crayfish

~Crayfish, also called crawfish or crawdad, are closely related to the lobster.

~More than half of the more than 500 species occur in North America, particularly Kentucky (Mammoth Cave) and Louisiana in the Mississippi basin.

~ Crayfish also live in Europe, New Zealand, East Asia and throughout the world, including the Tristan da Cunha Islands. Nearly all live in freshwater, although a few survive in salt water.

~Crayfish are characterised by a joined head and thorax, or midsection, and a segmented body, which is sandy yellow, green, or dark brown in colour.

~ The head has a sharp snout, and the eyes are on movable stalks. Crayfish are usually about 7.5 cm (3 inches) long.

characteristics of frog and crab~

                     CHARACTERISTICS of frog………….

v  Frogs have very good eyesight. They bulge out the sides of their heads in order for the frog to see in nearly all directions.  

v  Frogs also have amazing sense of hearing. You can often tell the difference between a male and female frog by the size of their eardrum, which can be seen behind their eyes. If the eardrum is smaller than the eye, the frog is a female. On males their eardrum is the same size as the eye.

v  Frogs have very powerful back legs and webbed feet that help them jump great distances, as well as, swim. Frogs even use their legs to dig, or burrow, underground for hibernating. Certain frogs can jump up to 20 times their own body length in a single leap. 

v  Every different species of frog has his or her own look. They come in many colors, patterns and sizes.

What are five characteristics of a frog?

1) need to live by water

2) smooth, moist skin

3) high, round eyes

4) teeth in upper jaw

5) long legs

      Characteristics of crab………

v  Crabs have one set of claws and four other pairs of legs. If a predator grabs a leg of a crab, the crab will shed it and later it will grow back.

v  Lined Shore crabs dance sideways down to the sea. They scrape small plants off rocks with the tiny cups on their pincers. The Lined Shore crab hides in the cracks of rocks.

v  Hermit crabs make their homes in empty snail shells. The hermit crab's back legs hold its shell on tight. The borrowed shells protect their soft bodies. As a hermit crab grows, it needs a bigger shell. Some hermit crabs will try and steal another's shell. They are scavengers who look for dead plants and animals that have fallen to the bottom of the tide pool.

v  The male crab shoots sperm into two hollows between the females back legs. That will make it possible for the female to lay eggs. When the eggs hatch, they are called zoea larva. The zoea larva feed in the ocean by trapping its food in its bristles. After a while the zoea larva change shape and are called megalopa larva. When the megalopa gets too heavy, it sinks to the bottom of the sea and starts to live as a crab. As the baby crab starts growing, it has to hide because its shell is soft. As it grows, its shell gets harder. Then when the crab gets too big for its shell, the shell cracks and falls off. This is called molting.

~Crabs have one set of claws and four other pairs of legs. If a predator grabs a leg of a crab, the crab will shed it and later it will grow back.

~Lined Shore crabs dance sideways down to the sea. They scrape small plants off rocks with the tiny cups on their pincers. The Lined Shore crab hides in the cracks of rocks.

~Hermit crabs make their homes in empty snail shells. The hermit crab's back legs hold its shell on tight. The borrowed shells protect their soft bodies. As a hermit crab grows, it needs a bigger shell. Some hermit crabs will try and steal another's shell. They are scavengers who look for dead plants and animals that have fallen to the bottom of the tide pool.

~The male crab shoots sperm into two hollows between the females back legs. That will make it possible for the female to lay eggs. When the eggs hatch, they are called zoea larva. The zoea larva feed in the ocean by trapping its food in its bristles. After a while the zoea larva change shape and are called megalopa larva. When the megalopa gets too heavy, it sinks to the bottom of the sea and starts to live as a crab. As the baby crab starts growing, it has to hide because its shell is soft. As it grows, its shell gets harder. Then when the crab gets too big for its shell, the shell cracks and falls off. This is called molting.

Green environment presentation slide...