arthropods: the marine bio version (chapter 5) phylum arthropoda largest and most successful phylum...
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Arthropods: The Marine Bio Version (chapter 5)
Phylum Arthropoda Largest and most successful phylum in the
animal kingdom. 75% of all animals! Exoskeleton made of Chitin (light/hard
polysaccharide). Must molt or shed exoskeleton to grow Jointed Appendages. Cephalization-compound eyes, ocelli
(eyespots), antennae. Segmented Bilateral symmetry
Classification you should know (there is a LOT more)
Subphylum Mandibulata Class crustacea
Order decapoda- lobsters
Subphylum Chelicerata Class meristomata- horseshoe crabs
Subphylum Uniramia (not elaborating)
Insects, millipeds, and centipedes
SUBPHYLUM MANDIBULATATA
Antennae, Mandibles & Maxillae Crustaceans-add some limestone to the
chitinous exoskeleton. Lobsters & crabs are the giants of this group-
most are a few centimeters long.
Class Crustacea
Shrimps, crabs, lobsters 2 pairs of antennae-sense
surroundings Dominant arthropods in sea (as
insects are on land) Appendages to swim, crawl,
attach, mate, feed
Crustaceans
lobsters & crabs, shrimp, copepods and barnacles.
rigid exoskeleton, crustaceans must “molt” or shed their shell in order to grow.
use an enzyme to split their shell & then crawl out.
molting horseshoe crab!
1) Small Crustaceans
Copepods- extremely abundant, planktonic, filter feed
Barnacles- usually sessile, filter feed, body enclosed by calcareous plates
Krill- planktonic, shrimp-like, have carapace to cover anterior, filter feed
the life of a Krill
2) Larger Crustaceans-Decapods: shrimps, lobsters, and crabs
Five pairs of legs, first pair are claws
Carapace encloses cephalothorax (anterior region)
(posterior region) is abdomen
Shrimps and Lobsters
Long abdomens (tails we eat) Scavengers for food Lobsters prey on mollusks
Christmas Island Crab Migrations History of the island crabs vs. cars
Hermit Crabs
Not true crabs Scavengers Hide abdomens in empty shells
True Crabs
Small abdomen and tucked under cephalothorax
V-shape ab. in males U-shape ab. in females Largest and most diverse of
decapods Scavengers and predators
Male Jonah Crab
Female Jonah Crab
Feeding Observe feeding appendages at work!
Maxillipeds- appendages near mouth (decapods have 3 pairs)
Food passes to stomach w/ teeth for grinding
Digestive glands w/ enzymes Intestine leads to anus Nutrients distributed through open
circulatory system
Response (nervous)
Well developed sense organs Compound eyes (opposite of
simple-14,000 sensitive units) Keen sense of smell Body postures/movements to
communicate w/ each other Simple brain
Compound Eyes- one way to respond to your environment- be able to see what is nearby!
Reproduction
Separate sexessexual reproduction
Males directly transfer sperm to females
Ex. Barnacle stretches out appendage to local females
Mating occurs after female molts
SUBPHYLUM CHELICERATA
Fang-like mouthparts (Chelicerae)-Pedipalps for sense. 2 Classes.
Class Merostomata-Horseshoe crabs.
Book gills on ventral surface
More closely related to spiders than crabs!
Horseshoe Crab
1. Carapace 2. Telson 3. Compound eye 4. Anterior spine Five pair of legs
LAB WORK:
DISSECTING A CRAYFISH
Virtually same structure as a lobster or shrimp, but has a better size than shrimp, and a better price than lobster!