arthropods. phylum: arthropoda common name = arthropods ex. insects, spiders, crabs, shrimp,...
TRANSCRIPT
Arthropods
Phylum: Arthropoda
• Common name = arthropods• Ex. Insects, spiders, crabs, shrimp, centipedes,
lobsters, ticks
Week 6
Monday
Arthropods
• Arthropods have:– Segmented body
• Head• Thorax • Abdomen
– Tough exoskeleton made of chitin– Jointed appendages
Cephalothorax⇛
Evolution of Arthropods
• Led to – Fewer appendages– Few segments– Highly specialized appendages
• Antennae• Pincers• Walking legs• Flippers• Claws
Feeding
• Herbivores, carnivores, omnivores
• Bloodsuckers, filter feeders, detritivores, parasites
• Mouthparts range from pinchers to fangs to sickle-shaped jaws depending on diet
Respiration
• Terrestrial– Breathe thru a network of branching tracheal
tubes– Air enters through spiracles = little openings along
body– Spiders uses book lungs
• Aquatic – Featherlike gills– Horseshoe crabs have book gills
Circulation
• Open circulatory system• Well-developed heart
Excretion
• Terrestrial– Malpighian tubules = saclike organs that extract
wastes from the blood and add them to feces (digestive wastes)
• Aquatic– Diffusion
Response
• Well-developed nervous system
• All have a BRAIN
Movement
• Muscles are attached to exoskeleton
• Pull of muscles against exoskeleton allows arthropods to move
• All have jointed appendages
Reproduction
• Terrestrial– Internal fertilization
• Aquatic – Internal or external fertilization
Growth and Development
• Exoskeletons DO NOT GROW, arthropods must MOLT
• Molting = arthropod sheds entire exoskeleton and makes a new larger one
• Molting arthropods are vulnerable and hide until they are done
Crustaceans
• Primarily aquatic• Crabs, shrimps, lobsters, crawfish, barnacles• 2 pairs of branched antennae• 2 or 3 body segments• Chewing mouthparts = mandibles
Tuesday
Associated Vocabulary
• Cephalothorax = fused body segment consisting of head and thorax
• Abdomen• Carapace = part of exoskeleton that covers the
cephalothorax• Mandible = biting, grinding mouthpart• Chelipeds = claws• Swimmerets = flipper-like appendages for
swimming
Chelicerates
• 2 body segments• Most have 4 pairs of walking legs• Horseshoe crabs, spiders, ticks, scorpions
From Prentice Hall Biology, 2006
Eyelash mites
Demodex folliculorum
Brown Recluse
Black Widow
Associated Vocabulary
• Chelicerae = mouthparts with fangs for stabbing and paralyzing prey
• Pedipalps =mouthparts for grabbing prey• Book lungs• Book gills• Spinnerets = organs in spiders that contain silk
glands for spinning webs
Uniramians
• Contains more species than all other animal groups combined!
• Jaws• 1 pair of antennae• Unbranched appendages• Insects, centipedes, millipedes
Centipedes and Millipedes
• Millipedes– Highly segmented body– 2 pairs of legs per segment– Live under rocks and decaying logs– Roll up or secrete toxins for defense
• Centipedes– 1 pair of legs per segment– Carnivorous and venomous– Live under rocks or in soil in humid areas
Insects
• 3 body segments = head, thorax, abdomen• 3 pairs of legs• 1 pair of antennae• 1 pair of compound eyes• 2 pairs of wings
Wednesday
Insects are the largest class of
animals!
Response to Stimuli
• Compound eyes with many lenses detect tiny movements and color changes
• Chemical receptors on mouthparts, legs and antennae (taste/smell)
• Well-developed ears (grasshoppers have ears on their legs!)
Adaptations for Feeding
• 3 pairs of appendages used as mouthparts– Mandibles to saw/grind (ex. ant)– Tube-like mouthpart to suck nectar (ex. moth)– Sponge-like mouthpart to lap up food (e. fly)
• Digestive enzymes in saliva – Bee saliva changes nectar from flowers into honey
Movement and Flight
• 3 pairs of legs– Walking, jumping, capturing/holding prey– Many species have spines or hooks on legs
• 2 pairs of wings made of chitin
• Evolution of flight allowed insects to disperse long distances and colonize many habitats
Metamorphosis
• Process of changing shape and form
– Complete metamorphosis• Egg-larva-pupa-adult• Larva looks nothing like adult
– Incomplete metamorphosis• Egg-nymph-adult• Nymphs look like adults
Advantage = larva and adults don’t compete for resources
Insects and Humans
• Beneficial– Honey– Wax– Pollination – Silk– Food
• Harmful– Damage wood– Damage clothes– Stings– Crop damage– Disease
Insect Communication
• Audio– Crickets
• Visual– Fireflies
• Chemical– Bees – Pheromones
Insect Societies
• Society = a group of closely related animals of the same species that work together for the benefit of the whole group– Bees– Ants– Termites
• Castes = groups of individuals that perform specific functions