Chapter 11-Arthropods Flashcards
Which phylum is the largest and most successful group of animals?
Phylum Arthropoda
What percentage of all species is in Arthropoda?
80%
What is the reason for the success of arthropods?
tremendous adaptability, found in every environment, dominant in marine, freshwater, terrestrial, and aerial habitats; one of three taxa to exhibit powered flight and one of two taxa adapted to withstand life in dry environemnts
What is another name for molting?
edysis
What are characteristics of a typical arthropod?
bilaterally symmetric, segmented body, jointed appendages
What are segments on the body that form functional groups called?
tagmata
T/F Tagmata can either be fused or moveable.
True
How many tagmata do insects have?
3-head, thorax, and abdomen
How many tagmata do spiders have?
2-cephalothorax and abdomen
What kind of coelom do arthropods have?
true coelom
What is the coelom like in arthropods?
greatly reduced and its role as the main body cavity has been supplanted by fluid-filled hemocoel
T/F Arthropods have a closed circulatory system.
False: they have an open circulatory system
What is blood called in arthropods? How is it pumped?
hemolymph-pumped through the heart inshore arteries before filling the hemocoel which surrounds the internal organs
What is the nervous system of arthropods like?
brain, pair of connectives that encircles the gut just posterior to the brain, paired ventral nerve cord with segmental ganglia
What does the respiratory system consist of?
gills or tracheae
What is the success of arthropods explained in large part by?
segmented body plan, jointed appendages, and exoskeleton
What did jointed appendages allow for?
develop efficient modes of locomotion both in water and on land
What do exoskeletons provide?
protection against predators, an internal attachment surface for muscles that move limbs (and wings in the case of insects), and a barrier against desiccation in terrestrial environments
What is a cuticle?
hard, thick structure composed primarily of nitrogenous polysaccharide chitin; folds inward to form support structures as well as the tracheal system and portions of the alimentary canal; allow animal to move by staying think and flexible
Is the cuticle shed?
yes; periodically since it does not increase with animal growth
What are the 4 major groups of arthropods?
- chelicerates (spiders, scorpions, and the kin) 2. myriapods (centipedes and millipedes) 3. crustaceans (crabs and their kin) 4. insects
What are the 3 extant subphyla of Arthropoda?
Chelicerata, Crustacea, and Uniramia
What does Uniramia include?
myriapods and hexapods
What are characteristics of Uniramia?
well-defined head, single pair of antennae, and a tracheal system
T/F Insects share a closer affinity with myriapods than crustaceans.
False-closer affinity with crustaceans
What are phylogenies?
hypotheses about evolutionary relationships among organisms, and subject to falsification and revision
What are trilobites?
extinct; had a chitinous exoskeleton, segmentation, and paired jointed appendages, well-developed compound eyes similar to those of insects; abundant and widely distributed in Paleozoic seas from the lower Permian to Cambrian
What organisms are chelicerates?
spiders, harvestman, scorpions, mites, ticks, and horseshoe crabs, among others