7 Arthropods

Features of Arthropods

Arthropod Diversity

Characteristics of Arthropods

Segmentation

Compound Eyes

Exoskeleton

Molting

Respiration

Excretion

W ater and small dissolved particles in the blood move through the tubules and into the arthropod’s gut. As this fluid moves through the gut, most of the water, valuable ions, and metabolites from the fluid are reabsorbed into the arthropod’s body tissues. Metabolic wastes remain in the gut and eventually leave the body through the anus.

Arthropod Diversity

Arachnid Modifications

Spiders

Brown Recluse Spider Characteristics

Reproduction During mating, the male uses its pedipalps modified into sperm storage organs to insert sperm into the female's body. The female lays an average of eggs inside a silk cocoon that she spins and hangs on her web. Poison Gland Poison glands are connected to the fanged chelicera. The venom of the brown recluse is harmful to many humans. The severity of a person’s reaction depends on the individual’s sensitivity and how much venom is injected. Respiration Book lungs contain stacks of thin blood-filled plates of tissue. Air enters the book lungs through slits on the underside of the spider’s abdomen and passes over them. Blood flowing through the plates picks up oxygen by diffusion.

Spiders

Scorpions

Mites

Many aquatic mites are herbivores, while terrestrial mites are usually predators. Most mites are not harmful, but some are plant and animal pests. While feeding, plant mites may pass viral and fungal infections to the plant. Blood-sucking ticks attach themselves to a host, often a human. Lyme disease is spread by bites from infected deer ticks.

onglegs.htmlspiders.ucr.edu/daddyl onglegs.html

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 Limulus polyphemus, Carcinoscorpius rotunda, and Tachypleus gigas.

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. Horseshoe Crab

Insect Diversity

Orders of Insects OrderExamplesNumber of species Coleoptera “shield winged” Beetles, Weevils 350,000 Diptera “two winged” Flies, Mosquitoes 120,000 Lepidoptera “scale winged” Butterflies, Moths 120,000 Hymenoptera “membrane winged” Ants, Wasps, Bees 100,000

Insects

Insect Body Plan

Insect Life Cycle

Complete Metamorphosis

Incomplete Metamorphosis

Flight Basic motion of the insect wing in insect with an indirect flight mechanism scheme of dorsoventral cut through a thorax segment with a wings b joints c dorsoventral muscles d longitudinal muscles

Flight

Social Insects

Insect Relatives

Crustacean Habitats

Crustaceans

Comparison of Crustaceans and Insects CharacteristicCrustaceansInsects Nature of AppendagesMost are branched at the endUnbranched at the end AntennaeTwo pairsOne pair Chewing AppendagesUsually three pairsOne pair Location of AppendagesCephalothorax and AbdomenHead and Thorax RespirationGillsTracheal System

Terrestrial Crustaceans

Aquatic Crustaceans

Decapods

Sessile Crustaceans