1. Phylum Arthropoda aka: Arthropods
Literally means “Jointed foot” animals
Includes crabs, shrimps, barnacles, spiders, insects, horseshoe crabs, etc…

2. Common Characteristics of all Arthropods
Exoskeleton-tough outer covering made of chitin (a carbohydrate). Some chitin may contain calcium to strengthen the skeleton. Protection and muscle attachment.
Jointed appendages that are specialized for feeding, movement, protection, and reproduction.

3. Class Crustacea a.k.a. Crustaceans
Bilateral Symmetry
2 main segments-cephalothorax and abdomen
Cephalothorax-head and chest region; covered with carapace
Abdomen-posterior region often including a tail.
Decapods (lobster, crabs, shrimps) 5 pr of legs under carapace. (not barnacle)
1st pair= claws for food getting; 2nd-5th pr walking
Head-two eyes, 2 pr. Antennae, special mouth parts for feeding.
Thorax-chelipeds (claws), and walking legs.
Abdomen-swimmerets (paddle-like appendages for swimming).

4. Lobsters
American lobster (Homarus americanus)- American or Maine lobster w/ 2 large claws
Spiny lobster (Planularis aragas)- no large claws; CA, FL, and Gulf of Mexico

5. American Lobsters
Most are greenish brown, maybe a little bluish with a little more red on the tips of the claws.
Mutants!!
One in two million lobsters are blue. DNA codes for a special protein that mixes with the red pigment to create blue.
One in 30 million are yellow.
1 in 100 million are albino.
It is estimated the chances of finding lobsters with difference colorings on their left and right halves is 1 in 50 million

6. Anatomy of Crayfish

7. Growth: Molting Shedding of the exoskeleton
Occurs once or more per year
Soft-shelled crabs are newly molted crabs

8. Feeding and Digestion
Predators that eat mussels and sea urchins or scavengers
One-way digestive tract-mouth, esophagus, stomach, intestines, and anus

9. Respiration
Uses gills-featherlike structures located in the water-filled chamber under the carapace.
Each gill is attached to the upper end of a walking leg.
Rapid beating of mouth parts sends currents of water over the gills.
O2 diffuses in and CO2 out.

10. Circulation
Open circulatory system (no capillaries so blood just passes through tissue spaces)
Blood is blue b/c of pigment called hemocyanin (contains copper)
Blood is pumped through the body by a one-chambered heart.
Kiwa hirsute; yeti crab

11. Nervous System
Have a brain and ventral nerve cord to carry impulses and messages from the eyes and antennae.

12. Reproductive System Sexually Internal fertilization
External development
Male deposits sperm cells into the female’s abdomen in the seminal receptacle
As the eggs are released, they are fertilized by the sperm.
Holds eggs on her swimmerets for nearly one year.
Plankton when they hatch.

13. Crabs Mole Crab (Emertia)
Lives in turbulent surf zone along sunny beaches.
Has smooth body to burrow w/ its swimmerets.
Feathery antennae to catch microscopic organisms in the sand.

14. Fiddler Crab (Genus Uca)
Digs tunnels in sand along shores of bays and inlets.
Males have one large claw and one small.
Females have 2 small claws.

15. Hermit Crab (Pagarus longicarpus)
Lives in shallow coastal waters.
Has soft abdomen w/o exoskeleton so it finds an empty shell to live in.
Changes shells as it grows.

16. Spider Crabs (Libinia emarginata)
Slow moving due to lack of paddle-like appendages
So slow that algae and barnacles grow on it.
Giant spider crab of Japan can grow up to 4m long from leg to tip.

17. Life Activities Similar to lobster
Abdomen folded up between walking legs.
V-shaped abdomen is a male; U-shaped abdomen female.
Mostly eat dead plant and animal matter.

18. Shrimp: Common Species
Pink Gulf Shrimp (Penaeus duorarum)- popular seafood; 17cm in length
Common Shore Shrimp (Palaemonetes vulgaris)- smaller; scavenges in marshes
Mantis Shrimp (Spuilla empusa)- largest shrimp (25 cm in length); eat worms and small fish; found from Cape Cod to Brazil.
Cleaner Shrimp (Periclimenes)- lives on coral reefs and rides tropical fish in Caribbean and Gulf waters and eats parasites that are found on their skin.

19. Examples of Shrimp
Mantis Shrimp 
Cleaner Shrimp (below)

20. Copepods
Copepods ’s of species. Less that ½ cm long; eats diatoms; important part of zooplankton community; abundant in spring and winter

21. Krill
Krill (Euphasia)-cold water (Antarctica) relative of copepod; grow 5 cm in length; principal food source for filter-feeding (baleen) whales

22. Amphipods and Isopods
Amphipods- crustaceans that look like tiny shrimp that have flattened sides; scuds and beach fleas
Isopods- small crustaceans with flattened bodies (dorsoventrally) and seven pairs of legs; sea roach.

23. Giant Isopod

25. Barnacles
Acorn Barnacle (Balanus)- have overlapping, sharp calcium carbonate plates; live in uppertidal zone, attached to rocks and other hard surfaces
Filter Feeders- Have cirri to feed-six pairs of feathery appendages extend to catch phytoplankton and other food particles.
No gills- O2 in water diffuses into skin
Hermaphrodite- contains both testes and ovaries; internal fertilization - penis from one barnacle is inserted into another barnacle. Internal development - fertilized eggs develop into larvae and enter the plankton population.

26. Example of Barnacle
Gooseberry barnacle

27. Class Merostomata- Horseshoe Crabs (Limulus polyphemus)
Found in the Eastern Pacific off the coast of Mexico, US and Canada;
Most closely related to spiders and scorpions
Lack antennae and mouthparts
Have 2 compound eyes and 2 simple eyes
Have 6 prs of appendages
1st pair are pinching claws (cheliceras)
other 5 are for walking

28. Horseshoe Crab cont. Scavengers; feeds on dead matter
Book Gills- used for breathing and locomotion
Telson (tail)- helps it right itself if it is tossed over by a wave.

29. Life Cycle
Late Spring during high tide, females come to shore with smaller males clutched to their backs
Females dig holes and lay eggs; males fertilize them externally while still attached to their backs.
In two weeks, the eggs hatch into juvenile HS crabs (no larval phase)
Can live 20 yrs. Living fossil. (no change in 400 million years!)

30. Horseshoe Crab Mating
Eggs (below)

31. Marine Insects- Class Insecta
Live in bays and marshes; have chitinous exoskeleton and jointed appendages but only have 3prs of legs and have 3 body segments (head, thorax and abdomen)
Marsh Mosquito- use proboscis to draw blood from host; (only female bite)
Sand Fly- “no-see-um” very tiny!