1. Arthropods

2. Phylum Arthropoda  Greek for jointed feet  Crabs, shrimp, barnacles, Insects, spiders etc.  Largest phylum of animals with ~ 1 million known species Of all the animals on earth, 3 out of 4 are arthropods Of all the animals on earth, 3 out of 4 are arthropods  Have a tremendous ability to take advantage of just about every habitat.

3. Phylum Arthropoda  Evolution of exoskeleton Composed of chitin Composed of chitin Tough, rigid material allows for great protection and supportTough, rigid material allows for great protection and support Causes limitation in size Causes limitation in size In order to grow the arthropod must molt its exoskeletonIn order to grow the arthropod must molt its exoskeleton You wont see an arthropod as big as a squid or a whaleYou wont see an arthropod as big as a squid or a whale Right after molting arthropods are at their most vulnerable stateRight after molting arthropods are at their most vulnerable state

4. Phylum Arthropoda  Bilaterally symmetrical  Coelomate  Segmented Body Divided into 3 segments: head, thorax and abdomen Divided into 3 segments: head, thorax and abdomen  Evolution of jointed appendages Increased mobility / flexibility (legs) Increased mobility / flexibility (legs) Modified for feeding and senses (mouthparts) Modified for feeding and senses (mouthparts) Used for protection Used for protection

5. Arthropod Biology  Digestion Filter feeding, scavengers, predators Filter feeding, scavengers, predators Appendages closest to the mouth, such as the maxillipeds, are specialized to sort out food and push it toward the mouth. Appendages closest to the mouth, such as the maxillipeds, are specialized to sort out food and push it toward the mouth. 2 chambered stomach that has chitinous teeth or ridges for grinding and bristles for sifting. 2 chambered stomach that has chitinous teeth or ridges for grinding and bristles for sifting.  Open Circulatory System  Respiratory System Arthropods have developed 3 types of respiratory structures depending on their environment gills, tracheae, or book lungs Arthropods have developed 3 types of respiratory structures depending on their environment gills, tracheae, or book lungs

6. Arthropod Biology  Acute Senses Many produce pheromones (a chemical odor) in order to communicate and have highly developed senses Many produce pheromones (a chemical odor) in order to communicate and have highly developed senses Most have one pair of large compound eyes and 3 to 8 simple eyes Most have one pair of large compound eyes and 3 to 8 simple eyes A simple eye – is a visual structure with only one lens that is used for detecting lightA simple eye – is a visual structure with only one lens that is used for detecting light A compound eye – is a visual structure with many lenses. Each lens registers light from a tiny portion of the field of viewA compound eye – is a visual structure with many lenses. Each lens registers light from a tiny portion of the field of view  Reproduction Separate sexes with internal fertilization Separate sexes with internal fertilization

7. Arthropod Biology  Niche (What they do / their role): Arthropods are of great direct and indirect importance to humans Arthropods are of great direct and indirect importance to humans The larger crustaceans--shrimps, lobsters, and crabs--are used as food throughout the world The larger crustaceans--shrimps, lobsters, and crabs--are used as food throughout the world Small planktonic crustaceans, such as copepods, water fleas, and krill, are a major link in the food chain Small planktonic crustaceans, such as copepods, water fleas, and krill, are a major link in the food chain Approximately two-thirds of all flowering plants (angiosperm) are pollinated by insects Approximately two-thirds of all flowering plants (angiosperm) are pollinated by insects They function as decomposers They function as decomposers Arthropods are major carriers of disease

8. Phylum Arthropoda 3 Subphylums 1. Chelicerates 2. Crustaceans 3. Uniramia

9. Subphylum Chelicerates General Characteristics:  Chelicerates have six pairs of appendages, which are uniramous (unbranched) include a pair of chelicerae, a pair of pedipalps, and four pairs of walking legs include a pair of chelicerae, a pair of pedipalps, and four pairs of walking legs  Lack mandibles and antennae  Respiration is by means of book gills, book lungs, or tracheae.

10. Subphylum Chelicerates 3 classes: 1. Merostomata - horseshoe crabs 2. Pycnogonida - sea spiders 3. Arachnida - spiders, ticks, mites

11. Class Merostomata  Horseshoe Crabs Carapace covering bodyCarapace covering body Cephalothorax, abdomen, telsonCephalothorax, abdomen, telson 6 pairs of appendages6 pairs of appendages Research using bloodResearch using blood

12. 1. Class Merostomata  two different groups of marine organisms the eurypterids and the horseshoe crabs the eurypterids and the horseshoe crabs Eurypterids are now extinct (they lived 200 to 500 million years ago) Eurypterids are now extinct (they lived 200 to 500 million years ago) Horseshoe crabs feed on small invertebrates Horseshoe crabs feed on small invertebrates  Members of this class have a large shield that covers the cephalothorax.  The compound eyes are reduced  The second pair of appendages, the pedipalps, resemble walking legs.  They have a long, spike-like appendage called a telson that projects from the rear of their bodies. The horseshoe crab uses its telson to flip itself over if it got flipped on its back. It is not used for defense as one might suspect. The horseshoe crab uses its telson to flip itself over if it got flipped on its back. It is not used for defense as one might suspect.  Respiration is via book gills.

13. 1. Class Merostomata

14. 2. Class Pycnogonida  An example is a sea spider  Sea spiders appear to be a sort of marine "spider,"  approximately 1000 described species – all are marine  They feed by sucking juices from soft-bodied invertebrates through a long proboscis.  The body itself is not divisible into neatly- organized tagmata or regions as it is in most other arthropods.  An anterior region bears, besides the proboscis, three or four pairs of appendages, including the first pair of walking legs.

15. 2. Class Pycnogonida

16. 3. Class Arachnida  Spiders, ticks, mites, scorpions  over 60,000 described species – spiders make up the majority of those known species  They have 8 legs instead of 6 like insects have  Nearly all species are terrestrial  Respiration is via tracheae or book lungs  They have a two-segment body, made up merely of the thorax and abdomen. thoraxabdomenthoraxabdomen  The pedipalpi (leg-like mouthparts) of some species has instead been adapted for sensory, prey capture or reproductive functions. pedipalpisensory preyreproductivepedipalpisensory preyreproductive

17. 3. Class Arachnida  Arachnids are mostly carnivorous, feeding on the pre-digested bodies of insects and other small animals. carnivorous  Many are venomous - they secrete poison from specialized glands to kill prey or enemies. venomouspoisonvenomouspoison  Others are parasites, some of which are carriers of disease. parasitesdiseaseparasitesdisease

18. Arachnids

19. Subphylum Crustacea  Barnacles, crabs, shrimp, etc.  Head, thorax, abdomen  Specialized appendages-- antennae, mandibles, maxillae

21. Class Malacostraca Order Decapoda  5 Pairs of walking legs  Crabs, shrimp, lobsters  Krill—importance to food chain  Unique pattern of segmentation among crabs

22. Class Cirripedia  Barnacles  Filter feeders  Sessile (including on other living organisms)  Feathery appendages (legs) to filter food  Larvae swim then attach for metamorphosis

23. Class Copepoda  Copepods  Important plankton  Filter feeders  Stay afloat by enlarged appendages  Many parasitic