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Arthropods and Echinoderms
Biology I: Chapter 28
ARTHROPODS
ARTHROPODS
Arthropods
Phylum Arthropoda
Insects, crabs, centipedes, spiders
Segmented body
Tough exoskeleton made of chitin
Jointed appendages
Evolution of Arthropods
Fewer body segments
Highly specialized appendages for feeding, movement and other functions
- movement strategies
Form and Function in Arthropods
Complex organ systems; some only found only in this phylum
Tracheal tubes (respiration)
Open circulatory system
Excrete wastes through saclike tubules
Feeding
Herbivores, carnivores, omnivores, bloodsuckers, filter feeders, detritivores, and parasites
Mouthparts have evolved to allow them to eat anything imaginable
Pincers or fangs to sickle-shaped jaws that can cut through the tissues of captured prey
mosquito
centipede
butterfly
beetle
squid
spider
Respiration: Terrestrial Arthropods
Tracheal tube: one of many branching, air-filled tubes that extend throughout the body
Spiracle: small opening located along the side of the body through which air enters and leaves the body
Book lung: organ that has layers of respiratory tissue stacked like the pages of a book: used to exchange gases
Respire through feather-like gills (i.e. lobster and crabs)
The horseshoe crab respires through organs: book gills
Circulation
Open circulatory system
Well-developed heart pumps blood through arteries that branch and enter the tissues
Blood leaves the blood vessels and moves through sinuses, or cavities
The blood recollects in a large sinus surrounding the heart
It reenters the heart and is again pumped throughout the body