Wize High School Grade 11 Biology Textbook > Invertebrates: Part 2 - Molting [Under construction]
Arthropoda: Crustaceans (Crabs and Lobsters)
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Crustaceans
Crustaceans are important scavengers that clear the ocean of waste, they are also a large commercial food.
- Crabs, Lobsters etc.
- 40,000 - 50,000 living species
- Mostly marine, some freshwater and terrestrial
- Large size range
Morphology
- 2 pairs of antennae
- Compound eyes on stalks
- Multiple lenses in each eye
- Cephalothorax
- Carapace: shielded cover that protects dorsal and lateral sides of body
- sometimes protects abdomen too
- Mandibles: primary mouthparts
- Single segment for biting and chewing
- 2 or more appendages help guide food to mouth
- Limbs
- Thoracic limbs: for locomotion
- Abdominal limbs: diverse use
- Filter feeding
- Holding eggs
- Exoskeleton
- Hardened with calcium carbonate
- Gills
- For gas exchange
- Wide and flat, fluffy
- Highly vascularized
- Thin unsclerotized cuticle
- Some terrestrial crustaceans use trachaea Example: Pillbugs
Crustacean Life Cycle
- Highly variable
- Direct and Indirect development
- Separate sexes
- Except for barnacles (hermaphroditic)
- Copluate to transfer sperm
- Females brood eggs until they hatch
Ecology and Importance
- Important detritivores, scavengers and predators
- Some scavenge dead plant and animal matter
- Some predatory
- Some are commensalists or parasites of verts
- Planktonic crustaceans feed large number of verts Examples: Whales and fish
- Some filter feed
- Motile Examples: fairy shrimp
- Sessile Examples: barnacles
Practice: Crustaceans
Which of the following are true about crustaceans? (select all that apply)
Practice: Crustaceans
Crustaceans ______________ to transfer sperm, then the female _________________ the eggs.
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