Arthropods: The Marine Bio Version (chapter 5)

Phylum Arthropoda Largest and most successful phylum in the animal kingdom. 75% of all animals! Largest and most successful phylum in the animal kingdom. 75% of all animals! Exoskeleton made of Chitin (light/hard polysaccharide). Exoskeleton made of Chitin (light/hard polysaccharide). Must molt or shed exoskeleton to grow Must molt or shed exoskeleton to grow Jointed Appendages. Jointed Appendages. Cephalization-compound eyes, ocelli (eyespots), antennae. Cephalization-compound eyes, ocelli (eyespots), antennae. Segmented Segmented Bilateral symmetry Bilateral symmetry

Classification you should know (there is a LOT more) Classification you should know (there is a LOT more) Subphylum Mandibulata Subphylum Mandibulata Class crustacea Class crustacea Order decapoda- lobsters Order decapoda- lobsters Subphylum Chelicerata Subphylum Chelicerata Class meristomata- horseshoe crabs Class meristomata- horseshoe crabs Subphylum Uniramia (not elaborating) Subphylum Uniramia (not elaborating) Insects, millipeds, and centipedes Insects, millipeds, and centipedes

SUBPHYLUM MANDIBULATATA Antennae, Mandibles & Maxillae Antennae, Mandibles & Maxillae Crustaceans-add some limestone to the chitinous exoskeleton. Crustaceans-add some limestone to the chitinous exoskeleton. Lobsters & crabs are the giants of this group-most are a few centimeters long. Lobsters & crabs are the giants of this group-most are a few centimeters long.

Class Crustacea Shrimps, crabs, lobsters Shrimps, crabs, lobsters 2 pairs of antennae-sense surroundings 2 pairs of antennae-sense surroundings Dominant arthropods in sea (as insects are on land) Dominant arthropods in sea (as insects are on land) Appendages to swim, crawl, attach, mate, feed Appendages to swim, crawl, attach, mate, feed

Crustaceans lobsters & crabs, shrimp, copepods and barnacles. lobsters & crabs, shrimp, copepods and barnacles. rigid exoskeleton, crustaceans must “molt” or shed their shell in order to grow. rigid exoskeleton, crustaceans must “molt” or shed their shell in order to grow. use an enzyme to split their shell & then crawl out. use an enzyme to split their shell & then crawl out. molting horseshoe crab! molting horseshoe crab! molting horseshoe crab! molting horseshoe crab!

1) Small Crustaceans Copepods- extremely abundant, planktonic, filter feed Copepods- extremely abundant, planktonic, filter feed Barnacles- usually sessile, filter feed, body enclosed by calcareous plates Barnacles- usually sessile, filter feed, body enclosed by calcareous plates Krill- planktonic, shrimp-like, have carapace to cover anterior, filter feed Krill- planktonic, shrimp-like, have carapace to cover anterior, filter feed

the life of a Krill the life of a Krill

2) Larger Crustaceans- Decapods: shrimps, lobsters, and crabs Five pairs of legs, first pair are claws Five pairs of legs, first pair are claws Carapace encloses cephalothorax (anterior region) Carapace encloses cephalothorax (anterior region) (posterior region) is abdomen (posterior region) is abdomen

Shrimps and Lobsters Long abdomens (tails we eat) Long abdomens (tails we eat) Scavengers for food Scavengers for food Lobsters prey on mollusks Lobsters prey on mollusks

Christmas Island Crab Migrations Christmas Island Crab Migrations Christmas Island Crab Migrations Christmas Island Crab Migrations History of the island History of the island History of the island History of the island crabs vs. cars crabs vs. cars crabs vs. cars crabs vs. cars

Hermit Crabs Not true crabs Not true crabs Scavengers Scavengers Hide abdomens in empty shells Hide abdomens in empty shells

True Crabs Small abdomen and tucked under cephalothorax Small abdomen and tucked under cephalothorax V-shape ab. in males V-shape ab. in males U-shape ab. in females U-shape ab. in females Largest and most diverse of decapods Largest and most diverse of decapods Scavengers and predators Scavengers and predators

Male Jonah Crab

Female Jonah Crab

Feeding Observe feeding appendages at work! Observe feeding appendages at work! Observe feeding appendages at work! Maxillipeds- appendages near mouth (decapods have 3 pairs) Maxillipeds- appendages near mouth (decapods have 3 pairs) Food passes to stomach w/ teeth for grinding Food passes to stomach w/ teeth for grinding Digestive glands w/ enzymes Digestive glands w/ enzymes Intestine leads to anus Intestine leads to anus Nutrients distributed through open circulatory system Nutrients distributed through open circulatory system

Response (nervous) Well developed sense organs Well developed sense organs Compound eyes (opposite of simple- 14,000 sensitive units) Compound eyes (opposite of simple- 14,000 sensitive units) Keen sense of smell Keen sense of smell Body postures/movements to communicate w/ each other Body postures/movements to communicate w/ each other Simple brain Simple brain

Compound Eyes- one way to respond to your environment- be able to see what is nearby!

Reproduction Separate sexes  sexual reproduction Separate sexes  sexual reproduction Males directly transfer sperm to females Males directly transfer sperm to females Ex. Barnacle stretches out appendage to local females Ex. Barnacle stretches out appendage to local females Mating occurs after female molts Mating occurs after female molts

SUBPHYLUM CHELICERATA Fang-like mouthparts (Chelicerae)-Pedipalps for sense. 2 Classes. Fang-like mouthparts (Chelicerae)-Pedipalps for sense. 2 Classes. Class Merostomata- Horseshoe crabs. Class Merostomata- Horseshoe crabs. Book gills on ventral surface Book gills on ventral surface More closely related to spiders than crabs! More closely related to spiders than crabs!

Horseshoe Crab 1. Carapace 1. Carapace 2. Telson 2. Telson 3. Compound eye 3. Compound eye 4. Anterior spine 4. Anterior spine Five pair of legs Five pair of legs

LAB WORK: DISSECTING A CRAYFISH DISSECTING A CRAYFISH Virtually same structure as a lobster or shrimp, but has a better size than shrimp, and a better price than lobster! Virtually same structure as a lobster or shrimp, but has a better size than shrimp, and a better price than lobster!