CRUSTACEANS

Phylum…

Characteristics of Arthropods (review)  Segmented body  Bilateral symmetry  Jointed appendages  Exoskeleton of chitin  Molting…

Characteristics of Crustaceans  Exoskeleton hardened by calcium carbonate  Green Gland  Excretory (urine)  Head with 5 pairs of antennae  2 pairs of antennae (sensing surroundings)  1 pair of mandibles  2 pairs feeding appendages  Fused cephalothorax  Gills  Appendages for swimming, crawling, attaching to things, mating, feeding

Small Crustaceans 1. Cirripedia (“wispy feet”)  Barnacles  filter feed with wispy legs (cirripeds)  sessile cement by antennal glands upside down, in 2 nd larval stage  hermaphrodites! Fertilize their neighbors  movable plates open the shell

Barnacle Mating!!  Poorly-endowed barnacles overthrow 150-year-old belief Poorly-endowed barnacles overthrow 150-year-old belief by Ed Yong Nat Geo In absolute terms, the blue whale has the largest penis of any animal—a huge mobile appendage that can reach 10 feet in length. But the blue whale itself is enormous. If you take body size into account, the animal kingdom’s champion penis belongs to a much smaller creature, and one that often lives on the faces of whales. It’s the barnacle…. has the largest penishas the largest penis They do so with a huge penis, which blindly reaches across into neighbouring shells and deposits sperm inside. This giant organ can stretch up to eight times a barnacle’s own body length, making it proportionately the biggest penis in the animal world. Since most barnacles are hermaphrodites, every individual can fertilise and be fertilised by all of its neighbours. And if there’s no one else within reach, the barnacles apparently fertilise themselves.

2. Copepoda  zooplankton—most abundant animals on earth!  Eyespot  1st antennae used to swim  Filter feed or capture food  Many parasitic  Convert food to wax (high energy)

3. Isopoda (“same leg”)  Tiny! <2cm unless deep sea (huge!)  Main body has legs similar to each other  Dorsoventrally compressed (flat back)  Similar walking legs  Heart in abdomen  Many parasitic  Marsupium  Egg pouch til hatch  Pillbugs, fish lice

4. Amphipoda “double legs”  Tiny! <2cm unless deep sea (huge!)  Laterally compressed (flattened sideways)  “bent”—curved body  Jumping legs  Marsupium  Whale lice

5. Euphasidae  Krill—shrimplike plankton  Up to 6 cm  Head fused, carapace of “armor”  8 pairs walking legs  Exposed gills  Eggs on swimming legs  Common in polar waters— gigantic schools  Deep sea also HSs

Large Crustaceans 6. Decapoda (10 legs)  5 pairs walking legs  Gills protected in chamber  Gastric mill-food grinding cavity  Eggs on swimming legs  Shrimps, lobsters, crabs-- ~10,000 species!  Hermit crabs, fiddler crabs,  blue crabs, but NOT  Horseshoe crabs!

Horseshoe Crabs  Not “true crabs”  Living “fossils”  Ancestors from 450 mya, not much change  Horseshoe-shaped carapace, 5 pairs of legs  Beaches for reproduction