Arthropod

Phylogeny of Arthropods Arthropoda Annelids (worms) Onychophorans (worms w/legs) Chelicerates (spiders) Crustaceans (lobsters) Insects (butterflies) Trilobites (extinct) Worm-like Ancestor

General Characteristics segmented body jointed appendages bilateral symmetry secreted exoskeleton molting open circulatory system ventral nerve cord and brain                                                                                                                                            

Subphylum Trilobita (extinct) Subphylum Chelicerata DIVERSITY Numbers about 80% of all animals are arthropods estimated to be over 30 million arthropods far more of them than all other metazoan species combined in virtually every conceivable environment: marine, terrestrial, freshwater, and aerial habitats. Phylum Arthropoda Subphylum Trilobita (extinct) Subphylum Chelicerata Subphylum Crustacea Subphylum Uniramia (insects)

Chelicerata horseshoe crabs mostly terrestrial cephalothorax-abdomen 6 pairs cephalothoracic appendages chelicerae, pedipalps, 4 pairs legs no antennae

Limulus is a benthic scavenger and predator. Horseshoe Crab Limulus polyphemus, Carcinoscorpius rotunda, and Tachypleus gigas. Limulus is a benthic scavenger and predator. Prey include clams and other invertebrates that it digs for in the sand. The tail spine is used as a self-righting mechanism if the animal is overturned accidentally. Lives up to 19 years Reaches sexual maturity at about 9 to 12 years old

Horseshoe Crab Mates during spring and summer full and new moons, onto ocean beaches. Females lay up to 30 thousand eggs, which males fertilize before burying them in the sand These eggs provide a major food source for migrating birds along the Atlantic coast. Those that are not eaten hatch during the next high tide, and the tiny larvae are carried away to sea.

Biomedical

Blue Blood Harvest

Subphylum Crustacea two pairs antennae marine, freshwater, and terrestrial Primarily aquatic Free-floating larval stage 26,000+ known species

Subphylum Crustacea brine shrimp Shrimps Crabs Lobsters Copepods Barnacles

Respiration Gills blood is oxygenated by gills oxygen delivered to tissues by blood crustacean gills are usually associated with appendages

Open Circulatory System Closed Circulatory System

NERVOUS SYSTEM Side view of body showing relative position of circulatory (yellow), digestive (green), and nervous (blue) systems.

SENSE ORGANS receptors for light, vibrations, chemicals, equilibrium, gravity cuticle modified to form a vast array of receptors (sensilla) Mechanoreceptors Chemoreceptors Equilibrium and Gravity Statocysts Tympanal Organs Hygroreceptors Photoreceptors Pigment-cup Ocelli Compound Eyes

Ommatidia Compound Eye Lens Crystalline cone Pigment cells Facet Visual cells Nerve fibers from visual cells Optic nerve Ommatidia

REPRODUCTION fertilization may be external or internal in aquatic arthropods always internal in terrestrial species

Arthropod Development Zoea Nauplius Megalops

Camouflage Decorator Crab Sponge crab

Camouflage: anemone crab

coral guard crabs and pocilloporid corals

gall crabs and pocilloporid corals

Symbiosis

scarlet cleaner shrimp

sea cucumber crab and sea cucumbers

pompom crabs and sea anemones

crabs and sea anemones