Crayfish Pre-Lab

External Structures

Carapace• Appearance:

Hard outer shell

• Location:Exterior of the body

• Function:Tough exoskeleton made of chitin; protects internal organs

Antennae• Appearance:

2 long stalks

• Location:Front of head.

• Function:Sensory reception.

Chelipeds• Appearance:

Large pincher-claws

• Location:Anterior end; near the head

• Function:Used to grab food and for defense

Walking Legs• Appearance:

Long, thin legs

• Location:Ventral (belly) side, mid section

• Function:Movement

Swimmerets• Appearance:

Tiny feather-like legs

• Location:Ventral (belly) side near posterior

• Function:Help with swimming + grasping during mating

Uropods & Telson• Appearance:

Fan-like tail

• Location:Posterior (rear) end

• Function:Propel during swimming.

Mouth• Appearance:

Tiny lips

• Location:Front of head/anterior

• Function:Eating, intake of food

Maxillipeds• Appearance:

Tiny claws

• Location:Under head and Chelipeds.

• Function:Bring food to mouth.

Internal Structures

Brain• Appearance:

Fleshy piece

• Location:Directly inside head, by eyes.

• Function:Controls organs + responses.

Digestive Glands• Appearance:

Light yellowish masses

• Location:1 on each side of head behind eyes

• Function:Secrete enzymes needed to digest food. Also called “green glands”

Stomachs• Appearance:

Fleshy light gray sacks

• Location:In between digestive glands

• Function:Grind up food (uses teeth-like structures).

Heart• Appearance:

Light brown lobe/flap.

• Location:Behind stomach + digestive glands

• Function:Pump + circulate throughout body

Intestine & Anus• Appearance:

Skinny tube + posterior opening

• Location:Leaving stomach, going down back.

• Function:Absorb nutrients + carry waste out of body.

Gills• Appearance:

White colored feathers

• Location:Sides of head, under shell.

• Function:Gas exchange (oxygen and CO2).

--Dissection Notes--

1. Lay crayfish on its belly.

2. Find carapace behind head.

3. Cut along lines + gently remove carapace.

4. Identify internal + external organs.

Virtual Dissection…

• https://www.youtube.com/watch?v=2cBGuEDxvNo

• https://www.youtube.com/watch?v=wSGEt1mY2OM

Internal (Dorsal):

Deeper Internal (Dorsal):

Internal (Lateral)

Abdomen (Dorsal):