Crab Dissection

Crab Dissection
On SCOPE's Things that…have a shell episode, you saw Julia dissect a crab. Here's how you
can do it at home:
Crabs are invertebrate crustaceans with 5 pairs of legs – the first pair of which is usually
modified as claws. They generally feed on algae, and can be found in fresh water but most are
marine animals, occurring at all depths of the ocean.
What you need:
An old shirt to wear to protect your clothes
Gloves
Tray
Uncooked crab (which can be bought from most fish shops)
What to do:
1. Find a good spot outside to do your dissection, as it can get quite smelly!
2. Put on the old shirt and gloves.
3. Place the crab on the tray and identify some of its body parts.
Carapace: Outer shell made
of chitin, protects the crab
from predators and provides
support to their organs.
Mouth
Antennae: allows
the crab to
interact with its
environment.
Legs: 1 pair
modified claws, 1
pair flattened for
swimming, 3 pairs
for walking.
Compound eyes:
mounted on the
end of stalks

4. Gently open the crab by lifting up the shell from the back. Make sure you do it slowly
and carefully, so you don't disrupt the organs inside. You will notice that the smell gets
a lot worse, but try to forget about that because there are some cool things to see
inside!
5. Identify some of its internal features.
Gill rakers:
sweep the
gills clean.
Gills: absorb
oxygen from
the water
Stomach:
digests food
Heart:
pumps
blood
around the
body
Flank: muscles, a part of
the crab that people eat!
6. When you're finished investigating the crab, place it in a plastic bag, then into the bin
and of course, wash out the tray.