Class Notes (839,146)
Canada (511,218)
Biology (Sci) (2,472)
BIOL 111 (283)

Arthropods II and Hormones

4 Pages

Biology (Sci)
Course Code
BIOL 111
Irene Gregory- Eaves

This preview shows page 1. Sign up to view the full 4 pages of the document.
25/10/11 Arthropods II Hormones = chemical messenger substance produced by endocrine system Ex. Termite behavior and morphology differences is induced by hormones released because of the environment and pheromone cues Diversity: 4 groups: 1. Myriapod: millipedes and centipedes 2. Chelicerates: spiders and mites and scorpions 3. Crustaceans: dominant marine environment 4. Hexapods: dominant in terrestrial environment, includes insects 1. Myriapods: countess feet 2 regions: head, trunk - Centipedes (chilopoda): - 1 pair of appendages per segment - Carnivores - less diverse - Millipedes (diplopoda - 2 pairs of app. Per segment - detritovores, herbivores - more diverse 2. Chelicerates: - have chilicerate (modified head appendage) Ex. Horseshoe crabs, pycnogonids, arachnids - No jaw (mandibles) - 2 body regions: cephalothoraxes – appendages, abdomen – no appendages - Pairs of appendages: 1. Chelicerae – fangs 2. Pedipalps – copulatory organs, pincers 3. Walking legs (4 pairs) 3. Crustaceans: Ex. crabs, daphnia, barnacles, etc… - Dominant marine arthropods in freshwater and terrestrial environment - Head + thorax or cephalothorax + abdomen - Appendages off each segment - Compose “zooplankton” important food source for fish 4. Hexapods: - largest groups - abundant in all enviros but deep sea - 3 body regions: - head: antennae, mouthparts - thorax: 3 pairs of walking legs maybe wings - abdomen: no appendages - non-insect hexapods have internal mouth parts 25/10/11 Insects: Unique to insects is their external mouthparts  huge diversity for consumption/feeding - herbivores, detritovores, fluid drinkers, predators, scavengers, parasites Flight: wings ~320mya a) ancestral multi-branched appendage b) in crayfish = gas exchange c) in drosophila = wings Wings have been secondarily lost in some species Respiratory system: - Insects and most myriapods: holes (spiracles) open into tubular tracheae which branch to finer tubes, carry O 2o body cells - Crustaceans: have gills - Chelicerates: have spiracles and trachea, book gills/book lungs - Book gills: in horseshe crabs: look like pages in a book - Book lungs: have similar structure but internally (in spiders, scorpions), protected for gas exchange prevent lungs from desiccating Open circulatory system: - Dorsal tubular heart (1 chamber) with pores (ostia) drives blood into hemocoael spaces - One-way valves Feeding: - Spend energy to acquire it: - Emergences: Insects responding to environment and making nearly faithful copies of themselves Ex. May fly emergence triggers: streams had low flow and hot temperature discovered in environmental survey - experiment: studied emergence by varying stream flow and temperature Sexual reproduction: - Most species are dioecous (sexes are separate) - lay eggs (exception: scorpion, holds eggs in female abdomen then babies sit on female back until 1 molt) - On land: Internal fertilization - some use spermatophoes = waterproof packets of sperm, when fertilization not completely internal - In Water: internal (crabs, only occurs right after molting) or external (barnacles) Daphnia life cycle: 25/10/11 - Parthenogenic cycle
More Less
Unlock Document

Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.