The document provides an overview of crabs, categorizing them within the animal kingdom and detailing their characteristics, reproduction, and importance in the ecosystem. Crabs are decapods with a varied lifespan and can live in both land and water, typically reproducing by laying eggs that have a low survival rate to adulthood. Additionally, crabs serve as a vital food source for marine animals and contribute to climate change mitigation while being nutritionally beneficial for human consumption.

1. Crabs and Cyclops
Presented by group 11

2. Classification of crabs
Kingdom ;Animalia
Phylum ;Arthropoda
Class ;Malacostraca
Oder ;Decapoda
Family ;Brachyura
Scientific N ;Brachyura
Common name ;Crabs

3. General introduction .
Crabs are sea creature with a flat round body covered by a
shell ,and five pair of legs with large claws on the front pairs
crabs usually mover sideways .the can actually move in all
direction ,but mostly run sideways , crabs are decapods
meaning the have 10legs female crabs usually release 1000 to
2000 eggs at once .the live span of a small crab averages
around 3-4 years but larger species such as the giant Japanese
spider crab can live as long as 100 years

4. General characteristics of crabs
Most crabs are decapods meaning that the have one legs
Double antennae most grabs processes a pair of antennae
The move slide way
The live both in land and in water
The are generally made of a thin exoskeleton composed primarily of
chitin with a pair of chelae [claws]
The vary in size from pea crabs ,a few millimeters wide ,and the Japanese
spider crab with a leg span up to 4m
The feed on small fish ,dead animals small clams see weeds and some
algae

20. Reproduction in crabs
• All species of crabs reproduce by lieing eggs but the male and the female still
have to fertilize the eggs
• During meeting the female crab carry the male on his back for up to two
weeks after which the female stores the male sperms in backs on her
abdomen .
• Female crabs can only mate after they molt or shed their shell ,when the
female is about molt ,she release a pheromones that help attract men to
come and fight over the female

21. When the female finally chooses a male , it attaches herself to the male and
rids with him on her back until she finally molts
After the molt , she then accepts the sperm from the male but she continues
to ride on her back until her new shell is finally hardened
Once the female actually detaches her self from the male she eventually
move to a different area and then allow the sperms to flow over it eggs to
fertilize them
Most species of crabs may carry about 100000tro 2000000 eggs but only a
few of them will ever crow to adulthood
The eggs are then stored on a sponge like structure for several weeks until
the larvae finally hatches
Many species of crabs usually meet only once these is because during
fertilization the female store enough of sperms in her abdomen to fertilize
two or three more sets of eggs

22. Importance of crabs
there are a vital food source to sea animals like the seals the whales the
penguins
The also help mitigate carbon from the atmosphere which can help to
mitigate the effect of climate change
The are rich in vitamins and minerals and also contain low amounts of fat
and contain omega 3 polyunsaturated acids which help provide protection
from heart disease and aid brain development
The contain selenium which play am important role in the immune system

23. THANK YOU