Crabs (= brachyuran decapod crustaceans) are found in Jurassic to Holocene sedimentary rocks. Complete or near-complete specimens are scarce. They have a relatively shortened carapace, compared to lobsters and crayfish, and have the abdominal section of the body turned underneath & essentially fused with the carapace. Small to large claws (chelae) occur at the distal ends of the 1st pair of appendages. Decapods have 5 pairs of appendages - 10 in all - “decapod” means “ten-legged”.
Most crabs are marine (oceanic), but some forms are freshwater or terrestrial. Their feeding habits range from predation to scavenging to algal grazing to filter feeding, etc.
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
https://creativecommons.org/licenses/by/2.0CC BY 2.0 Creative Commons Attribution 2.0 truetrue