Segmented worms, earthworms, marine worms, etc. No mouthparts or antennae, Bilateral symmetry
Body composed of many segments, mouthparts present, segmented antennae present, have many paired appendages that are used for walking, but these leg-like structures are not segmented, Bilateral symmetry, Breath with a system of internal tubes (tracheae)
(Arthropoda) Body composed of many segments, Body segments grouped in 2 or 3 regions with specialized functions, Paired segmented appendages, Segmented mouthparts, segmented antennae, Bilateral symmetry, Tracheae, exoskeleton
(Trilobita) - marine creatures that became extinct
1 pair of antennae, Remaining appendages similar and leg-like, Body with 3 major regions (cephalon, thorax, and pygidium)
Water fleas plus the decapods and isopods
-Mouthparts are mandibles that move laterally, 2 pairs of antennae, All appendages have 2 brances, although sometimes one of the branches is hard to distinguish, Usually 2 body regions (cephalothorax and abdomen.
Lobsters, crayfish, shrimp, crabs
- Body is cylindrical
-5 pairs of walking legs
Roly-polys, sowbugs, pilibugs
- Body is flattened
- 7 pairs of walking legs
Mouthparts are fang-like, pincers (chelicerae) that move vertically, no antennae, All appendages have 1 branch, 2 distinct body regions (cephalothorax and abdomen)
Near the chelicerae they have a pair of appendages called pedipalps that are used for sensory purposes or to assist with feeding, 4 pairs of jointed appendages that are used for walking or crawling
Abdomen has segments, stinger on the end of abdomen, pedipalps are very long (often as long legs) and large, with claws on end
Abdomen has no segments, Abdomen is very narrow where it joins the cephalothorax, Pedipalps are shorter than legs and narrow, finger-like
Order: Ticks and Mites
Abdomen has no segments, Abdomen is broad where it joins the cephalothorax, Chelicerae and pedipalps are very short
Order: Daddy longlegs
The daddy longlegs are the most common member of this order
- Abdomen has segments, No stinger on the end of abdomen, Very long, thin legs
Mouthparts are mandibles that move laterally, 1 pair of antennae, all appendages have 1 branch, either 2 body regions or 3 body regions
2 body regions (head and elongate abdomen), 30 or more pairs of legs, with 2 pairs on most body segments.
2 body regions (head and an elongate abdomen), 15 or more pairs of legs, with 1 pair on each body segment, 1st pair of legs modified into a poison claw
Classification of Animals
Monera - bacteria
plantae - the higher plants
Fungi - the fungi
Animalia - the animals
Protesta - slime mods, protozoans
Almost all insects have
- 2 pairs of functional wings as adults
- No other class of arthropods has wings.
- 3 pairs of legs, with 1 pair on each of the 3 thorax segments
- Wings are on 2nd and 3rd thorax segments
The segmented hard skin of an arthropod, which is structurally extremely strong for a small organism like an isect. Acts like a suit of armor, made with chitin. Structurally similar to cellulose, like natural fiberglass
The destruction of old cuticle, formation of new and larger cuticle, and shedding of remnants of old cuticle. The old cuticle is partially used to make new one. New cuiticle tans, hardens, and takes color in a short time
Control of Molting
Controlled by endocrine system, and by brain. Gut receptors, elsewhere indicate stretching. Cells in brain secrete hormone that stimulates prothoracic gland. This gland produces a molting hormone called ecdysone.
3 segments of an insect
Head: sensory inputs and feeding
Thorax: Locomotion, sensory, and digestion
Abdomen" digestion, excretion, and reproduction
Different types of Feeding appendages in Insects
Chewing (beetles, grasshoppers)
piercing-sucking (Lice, mosquitoes)
Advantages to small size in insects
Can hide easier, and have more niches in which to live, need less food, Easier to disperse because they are carried by wind currents
Disadvantages to small size in Insects
Surface area to volume ratio, Having large surface areas with small volumes mean that insects lose water and heat easily.
Methods to solve the water loss problem in insects
Capture water by allowing it to condense on their abdomens, Reproduction is internal in insects, unlike external fertilization in some other arthropods. INsects use uric acid for their nitrogenous waste. It can be exceted as a dry pellet because it is relatively nontoxic and almost insoluble in water.
Allows insects to suspend development and usually occurs from a change in photoperiod. Irreversible once started, genetically programmed, can occur in winter (hibernal) and summer (aestival)
is a period of inactivity, which is a similar adaptation except it occurs in direct response to environmental conditions. Also, reversible, temporary, often short term.
is similar to cloning (no males necessary). Example: aphids Cons: no genetic diversity