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
How are chelicerates’ bodies divided?
2 tagmata: cephalothorax and abdomen
What are features of chelicerates?
lack mandibles for chewing, first pair of appendages called chelicerae are feeding appendages adapted for seeing and tearing, second pair of appendages called pedipalps serve as sensory role, remaining four appendages are walking legs, lack antennae
What are characteristics of Class Xiphosura?
horseshoe crabs; member of an ancient lineage of chelicerates, “living fossils”, bottom-dwelling marine organisms feed on mollusks, annelids, and dead fish, abundant on east coast of N. America
What are characteristics of Class Arachnida?
includes spiders, scorpions, mites, ticks, as well as many less familiar taxa; includes all living terrestrial chelicerates; have 2 magmata, spiders and mites make up 80%
What is different for the tagmata of scorpions and their relatives?
abdomen is segmented and subdivided into a pre- and post-abdomen
What are spinnerets? Which Order have this?
silk-spinning appendages located on posterior abdomen; Order Araneae
Are spiders carnivorous?
yes
What are the chelicerae equipped with?
poison glands; cause immobilization in prey
What organisms belong to Order Opiliones?
daddy longlegs or harvestman; not spiders
Do opiliones produce silk or poison?
no and do not bite
What are characteristics of Order Acari?
mites and ticks most diverse order of arachnids; generally small and lack obvious tagmata and segmentation
What are differences between ticks and mites?
mites smaller and softer-bodied than ticks, ticks tough and leathery; mites free-living, some parasitic on humans, domesticated animals, and crops; ticks are parasitic and responsible for transmission of diseases
What are characteristics of crustaceans?
possess mandibles (jaw-like appendages), at least one pair of antennae; gill-breathing mandibulate and some lack respiratory system altogether, 2 pairs antennae on head and pair of appendages on each body segment, some appendages are biramous (two-branched)
What organisms include crustaceans?
crabs, shrimps, crayfishes, lobsters, isopods, copepods, barnacles, among others
What is the carapace?
covers cephalothorax
What conceals the gills?
branchiostegites
What does bifurcate mean?
split into two branches
T/F The abdomen of crustaceans is made up of 6 segments?
True
Where are swimmerets on crustaceans?
first five segments
What does the sixth segment form?
telson
What do the myriapods include?
chilopods and diplopods
What are characteristics of myriapods?
2 tagmata (head and trunk), head bears single pair of antennae, trunk bears paired appendages on all but terminal segment
What are characteristics of Class Chilopoda?
centipeds active predators with poison fangs; each segment of trunk bears single pair of legs; between 15 and 191 pairs of legs, always an odd number
What are characteristics of Class Diplopoda?
secretive, nocturnal detrivores; generally long and cylindrical; segments bear 2 pairs of legs, no more than 710 legs
What organisms belong to Hexapods?
insects; wingless: Collembola (springtails, snowfleas), Protura, and Diplura
What are characteristics of insects?
3 tagmata (head, thorax and abdomen), 3 pairs of legs, one pair of antennae, and tracheal system, 2 pairs of wings
What are apterygotes?
wingless
What are the 3 segments of the thorax?
prothorax, mesothorax, and metathorax
What is a tympanum?
hearing organ located on each side of first abdominal segment
What are malphigian tubules?
filter for removing nitrogenous wastes from hemolymph
What is the exoskeleton of insects like and what’s unique?
tough, non-living outer cuticle that does not grow; growth by shedding exoskeleton periodically
What is another term for molting?
ecdysis
What are instars?
stages between molting
What is ametabolous development?
restricted to apterygotes, little physical change
What is hemimetabolous development?
more complex; juveniles (nymphs) share general appearance and feeding habits of adult but lack functional wings and external genitalia; undergo incomplete metamorphosis (no dramatic changes in body-form during development, have wing buds
What insects undergo hemimetabolous?
Odonata (dragonflies), Orthoptera (grasshoppers, crickets), Hemiptera (true bugs), and Homoptera (cicadas, aphid)
What is holometabolous development?
juveniles called larvae differ radically in appearance from adults and have different feeding habits; enter resting, non-feeding stage called pupa which animal’s tissues completely reorganize into adult form; undergo complete metamorphosis; larvae do not possess wing buds
What insects undergo holometabolous development?
Diptera (flies), Lepidoptera (butterflies, moths), Hymenoptera (bees, wasps, ants), and Coleoptera (beetles)
T/F In dragonflies, wings stay erect and do not fold.
True
What are characteristics of Hemiptera?
diamond-shaped membrane, sucking mouthparts, tent-like wings
What are characteristics of Diptera?
hind wings modified into stubby balance organs called halters, single pair of wings for flight
What are characteristics of Hymenoptera?
narrow joint of thorax and abdomen, 2 pairs wings, can look like flies
What are characteristics of Coleoptera?
have hard structures called elytra; hindwings used in flight and folded and protected beneath elytra, no triangle
