Arthropods BIS 2C

diagnostic features of ecydsozoans

external chitnous exoskeleton, ecdysis (exoskeletal molting)

diagnostic features of arthropods

jointed apendages, compound eyes with light-sensing structures called ommatidia, tagmosis

arthropod group: chelicerates

2 tagma (carapace and abdomen), four pairs of legs, chelicerae (feeding appendages), pedipalps (feeding/sensory organs, terrestrial ones have book-lung respiratory system

myriapods

1 tagma (head), many segments with one pair of legs (centipedes) or two pairs of legs (millipedes) per segment, respiratory system with spiracles (openings) and trachea (tubules).

malacostracan

3 tagma, head and thorax fused into a carapace, two pairs of antennae, terrestrial ones have a gill respiratory system.

hexapods

3 tagma, 3 pairs of legs, one pair of antennae, "apterygota" and insects, respiratory system with spiracles (openings) and trachea (tubules).

"apterygota"

small, flightless species with poorly developed respiratory systems, moist habitats.

insect innovations

flight once, metamorphosis

incomplete metamorphosis

hemimetabolism, Orthoptera and Hemiptera, series of molts till adult stage, instars (molts) lack wings, can't reproduce, eat same food as adults

complete metamorphosis

holometabolism, Hymenoptera, coleoptera, diptra, lepidotera, four stages of embryo, larva, pupa, and adult, different food sources for larvae and adults.

palaeoptera

two pairs of non-folding wings, aquatic nymph stages

orthoptera

"straight wing", chewing mouth parts

hemiptera

"half wing", true buts with piercing/sucking mouth parts

hymenoptera

two pairs of wings (fore and hind) connects by zipper like hamuli

coleoptera

"sheath wing", beetles with two pairs of wings, with forewings modified into hardened wing cases (elytra)

diptera

flies with two pairs of wings, hindwings modified into mechanosensory organs (halters)

Lepidoptera

two pairs of wings covered in tiny scales with tubular mouthmarts (proboscis) for siphoning nectar.