Arthropod and Mollusc Study Guide
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1. What are three characteristics of all Arthropods?
Segmented body, jointed legs, chitin exoskeleton
2. What is chitin?
Hard, lightweight, protective substance used to make arthropods’ exoskeletons
3. Compare and contrast how a crustacean and a grasshopper breathe.
Crustacean: breath using gills
Grasshopper: air comes in through spiracles
4. Why is an insect’s blood green?
Because it doesn’t carry oxygen
5. What is a radula?
A toothed-tongue in some mollusks. In gastropods it helps them scrape algae. In cephalopods it helps
them eat prey
6. How does a squid move?
Jet propulsion- water forced out of siphon helps them move, fins help them steer
7. Tell me about an arthropods circulatory system.
Open circulatory system- no blood vessels, instead blood surrounds internal organs
Blood is green because it doesn’t carry oxygen
8. What is molting?
When an arthropod sheds its old exoskeleton
9. List the three classes of Molluscs that we studied and give an example and a few
characteristics of each.
Gastropod- snails and slugs
Cephalopods- octopus and squid
Bilvalves- clams and oysters
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10. Know the external anatomy of a: crayfish, grasshopper, squid and internal anatomy of a
crayfish and squid.
a. Can you tell a male from a female crayfish?
b. Can you tell a male from a female grasshopper?
c. What special sense organs do they each use (for hearing, seeing, etc)
d. What special structures do each use in their excretory systems?
Be able to label the following:
Arthropod Dissections…
Grasshopper
Head
Thorax
Abdomen
Spiracles
Tympanum
Ocelli (simple eyes)
Compound Eyes
Wings
Male vs. Female (look for ovipositor on
female)
Crayfish
See Powerpoints
on my website,
note sheets, and
lab sheets to help
with these
questions!
Squid Dissection…
External
Mantle
Fins
Siphon
Tentacles
Eyes
arms
Internal
Gills
Mouth/Beak
Esophagus
Stomach
Caecum
Gonads (reproductive organs)
Cephalothorax
Abdomen
Carapace
Antennae and Antennules
Uropods and Telson
Walking Legs
Seimmerets
Chelipeds
Mouth parts (maxilla, maxillipeds,
mandible)
Male vs. Female (look for the modified
swimmerettes in Male)
Heart
Intestine
Green Gland
Digestive Gland
Stomach
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