This document summarizes key characteristics of chelicerata, an subphylum of arthropods that includes spiders, scorpions, and horseshoe crabs. It describes their physical features such as an exoskeleton and segmented body, as well as organ systems like their circulatory, respiratory, and digestive systems. Examples provided include the brown recluse spider, striped scorpion, and horseshoe crabs. Human interactions are also summarized, noting both medical impacts of some bites and use of venom in medicines.

1. Arthropoda Chelicerata (Eight- legged Arthropods) By Sydney Furth & Brenna Banderob 5/19/09 pr. 3 Anoplodactylus evansi (no common name)

2. Classification Subphylum breaks into classes: -Arachnida (arachnids) -Merostomata (horseshoe crabs) -Pycnogonida (sea spiders) Limulus polyphemus Horseshoe crab

3. Physical Features Exoskeleton Jointed limbs Segmented body Well developed nervous system Eight legs No antennae No distinct head Pseudopallene ambigua Yellow Pycnogonid

4. Reproduction Sexual reproduction Produces eggs Spider eggs

5. Feeding & Digestive System Digestive system divided into 3 parts -foregut -midgut -hindgut carnivores Sometimes eat other arthropods

6. Circulatory System Heart= long thin tube Blood travels through open passages Pale blood cells - bluish If skin broken- blood drains quickly

7. Respiratory System 2 breathing organs -tracheae -small tubes that carry air through body -book lungs -cavities in the abdomin -air enters from slits on either side

8. environment land arthropods can be found any where on land Water for horseshoe crabs & sea spiders (obviously) -fresh and salt water Spider web

9. Human Interactions Most people go EEEKK at the sight of 8-legged arthropods Many spider bites can cause problems, such as death Scorpion & spider venom is used to make powerful medicines & vaccines A bite from this caused this Loxosceles reclusa Brown recluse spider

10. Unique Features Cold blooded Most spiders have week vision Horseshoe crabs (who live in water) come ashore In large numbers to lay eggs Horseshoe crabs swim upside-down Centruroides vittatus striped scorpion

11. Examples Tarantula movie

12. Works Cited Myers, P. 2001. Chelicerata . Animal Diversity Web. May 19, 2009. <http://animaldiversity. umnz.umich.edu/site/accounts/information /Chelicerata.html> Holt, Rinehart, Winston. Animals. Austin, Texas: Harcourt Classroom Education Co., 2002 The Invertebrate Animals. May 20, 2009. <http://users.rcn.com/jkimball.ma.ultran et/BiologyPages/I/invertabrates.html> Eisen, Stan. Arthropoda chericerata . May 21, 09. <http://www.cbu.edu/~seisen/Arthropoda/sld 014.htm>

13. Spiders . May 21,09. < http://www.greensmith s.com/spiders.html > Thompson, ken. The bumble bee. May 20, 09. < http://www.bioteams.com/2006/04/2 1/the_social_networks.html>