BIOLOGY

Unit 7:Crayfish Notes

(1) External Parts• Carapace:

– Hard, red outer shell– Exoskeleton to protect internal organs

• Chelipeds:– Large pincher-claws– Used to grab prey

• Maxillipeds:– Smaller arms near mouth.– Used to shove food into mouth.

• Swimmerets:– Tiny, feather like legs (along belly)– Used to grasp during sex.

External Parts (Cont’d)• Antennae:

– Long stalks along top of head.– Sensory reception.

• Gills:– White, feathery like layers along sides of head.– Absorb oxygen from water (for breathing).

(2) In The Head• Encephalon:

– Fleshy bit, Directly inside head, by eyes.– (Brain) Control all other organs + respond.

• Green Gland:– 2 small flesh-sticks on either side of eyes.– Secrete enzymes needed to digest food.

• Stomach:– Sack full of bony teeth.– Directly behind head in center.– Breaks apart food.

(3) Chest & Abdomen• Heart:

– Light brown flap behind stomach, along back.– Pump + circulate blood across organs.– Open Circulatory System = No blood vessels,

organs bathe in blood.

• Intestine:– Skinny tube leaving stomach.– Absorb nutrients and excrete waste.

Male Parts• Appearance:

Tiny, bent legs

• Location:Belly

• Function:Insert sperm into female

Female Parts• Appearance:

Swollen hole

• Location:Belly, in between swimmerets

• Function:Take in sperm (like vagina)

--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.

External Dorsal:

External Ventral:

Sex:

MALE FEMALE

External (Lateral):

Internal (Dorsal):

Deeper Internal (Dorsal):

Internal (Lateral)

Abdomen (Dorsal):