crabs

16
THE CRABS

Upload: seguimosnadarineando

Post on 14-Feb-2017

128 views

Category:

Education


0 download

TRANSCRIPT

Page 1: Crabs

THE CRABS

Page 2: Crabs

• Crabs live all over the world.

• Some kinds, or species, live in salt water, others live in fresh water.

• Some even spend all their time on dry land.

Page 3: Crabs

SALT WATER CRABS

Page 4: Crabs

FRESH WATER CRABS

Page 5: Crabs

DRY LAND CRABS

Page 6: Crabs

These are the parts of

the body of a crab

Page 7: Crabs

This is another kind

of crab

Page 8: Crabs

WHAT DOES THE

CRABS EAT???

Page 9: Crabs

JOKING APART…

Crabs eat small bits of plant and animal material that they find in the water and along the shoreline.

Page 10: Crabs

CRABS

REPRODUCTION

Page 11: Crabs

All species of crabs reproduce by laying eggs, but the females and males still need to mate to fertilize the eggs.

During mating, the male crab carries the female on his back for up to two weeks, after which the female stores the male's sperm in sacs on her abdomen.

Page 12: Crabs

Female crabs can only mate after they molt, or shed their shell. When a female is about to molt, she releases pheromones that attract male crabs who then fight over the female.

When the female chooses a male, she then attaches herself to the male and rides on his back until she finally molts.

After the molting, she then accepts the sperm from the male, but she continues to ride on his back until her new shell has fully hardened.

Page 13: Crabs

Once the female detaches herself from the male, she then migrates to a different area and eventually allows the sperm to flow over her eggs to fertilize them.

Most species of crabs can carry as many as 100,000 to 200,000 eggs at one time, but many of these won't hatch and only a small percentage ever grow to adulthood.

Page 14: Crabs

The eggs are then stored on a sponge-like structure on the female's abdomen for a period of several weeks until the crab larvae finally hatch.

Many species of crab only mate once, but after fertilizing the initial set of eggs, the female continues to store enough sperm on her abdomen to fertilize two or three more sets of eggs.

Page 15: Crabs

The diferences

between male and female crabs

Page 16: Crabs