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Phylum Arthropoda aka: Arthropods

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

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Phylum Arthropoda aka: Arthropods

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  1. Phylum Arthropodaaka: 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-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-chilipeds (claws), and walking legs. • Abdomen-swimmerets (paddle-like appendages for swimming).

  4. Anatomy of Crayfish

  5. Molting • Shedding of the exoskeleton • Occurs once or more per year • Soft-shelled crabs are newly molted crabs

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

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

  8. 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.

  9. 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.

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

  11. Reproductive System • Sexually • Internal fertilization • Externaldevelopment • 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.

  12. Lobsters One in a million lobsters are blue. Mutant of the brown lobster DNA codes for a special protein that mixes with the red pigment to create blue.

  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(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 (Calanus)- 1000’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

  24. 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.

  25. Example of Barnacle • Gooseberry barnacle

  26. Class Merostomata- Horseshoe Crabs (Limulus polyphemus) • 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 pr are pinching claws (cheliceras); and the other 5 are for walking

  27. Horseshoe Crab cont. • Scavenge and 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.

  28. Life Cycle • Late Spring high tide, female HS crabs w/ smaller males clutched to their backs come to shore • 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!)

  29. Horseshoe Crab Mating • Eggs (below)

  30. 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!

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