1. Phylum Arthropoda “jointed appendaged animals’

2. Arthropods: Phylum Arthropoda
The phylum with the greatest number of species
Four lineages:
Trilobites (all extinct)
Chelicerates (spiders, mites, scorpions)
Crustaceans (crabs, shrimps, barnacles)
Uniramians (insects, centipedes, millipedes)

3. Adaptations for Success
Hardened exoskeleton
Jointed appendages
Fused and modified segments
Respiratory structures
Specialized sensory structures
Division of labor
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Figure Page 432

4. Chelicerates Originated in seas
A few are still marine: horseshoe crabs, sea spiders
The arachnids are all terrestrial
Spiders Mites
Scorpions Chiggers
“Daddy longlegs” Ticks

5. Subphylum Chelicerata
These are the scorpions, spiders, mites, horseshoe crabs, and "sea spiders." Chelicerates have six pairs of appendages, which are uniramous (unbranched). These include a pair of chelicerae, a pair of pedipalps, and four pairs of walking legs. Chelicerates lack mandibles and antennae. Respiration is by means of book gills, book lungs, or tracheae.

6. Class Arachnida
Arachnids have a pair of tagmata called a prosoma (cephalothorax) and opisthosoma (abdomen). The prosoma is partially or completely covered with a carapace-like shield. The opisthosoma may be segmented or unsegmented. The appendages on the opithosoma are absent or modified, being used as spinnerets (spiders) or pectines (probably sensory in function, found in scorpions). Respiration is via tracheae or book lungs; it is cutaneous in many small arachnids.

7. house spider Achaearanea tepidariorum

8. Body Plan of a Spider eye brain heart digestive gland
Malpighian tubule
poison gland
book lung
ovary
silk gland
anus
pedipalp
mouth
sperm receptacle
spinners
chelicera
Figure Page 433

9. beach wolf spider Arctosa littoralis

10. Crustaceans
Most are marine, some freshwater, a few terrestrial
Head has two pairs of antenna, three pairs of food-handling appendages
Copepods
Crayfish
Barnacles
Lobsters
Shrimps
Crabs
Isopods (pillbugs)

11. Lobster Body Plan Figure 25.29a Page 434 one of two eyes
fused segments of cephalothorax
segments of abdomen
antennae (two pairs)
food-handling appendages (three pairs)
swimmerets
tail fin
first leg
Figure 25.29a Page 434
five walking legs (five pairs total)

12. Subphylum Crustacea (crustaceans)
Members of the Subphylum include lobsters, crabs, crayfish, shrimp, copepods, barnacles, and several other groups of organisms. All have two pairs of antennae, a pair of mandibles, a pair of compound eyes (usually on stalks), and two pair of maxillae on their heads, followed by a pair of appendages on each body segment (crustacean bodies usually are made up of head, thorax, and abdomen, although the segments composing these tagmata differ among different Classes). The appendages are primitively branched (biramous), and although this condition is modified in many species, adults always have at least some biramous appendages. Crustaceans respire via gills. Like other arthropods, all have a hard but flexible exoskeleton.

13. blue crab Callinectes sapidus

14. Daphnia pulex

15. rusty crayfish Orconectes rusticus

16. yellowline arrow crab Stenorhynchus seticornis

19. Uniramia
Uniramians are arthropods whose appendages are unbranched. Most appendages are made up of several articulating pieces. The uniramian body has two or three tagmata, and the abdomen contains numerous segments. The head appendages include paired antennae and mandibles, and also two pairs of maxillae (the second pair may be fused or sometimes absent). "Breathing" is by means of tracheae and spiracles. The sexes are separate, but most other aspects of reproduction are extremely varied.

20. Class Insecta (insects)
A number of features, however, are shared by most kinds of living insects. In addition to the general characteristics of uniramians, these include a body composed of three tagmata, a head, thorax, and abodmen; a pair of relatively large compound eyes and usually three ocelli located on the head; a pair of antennae, also on the head; mouthparts consisting of a labrum, a pair of mandibles, a pair of maxillae, a labium, and a tonguelike hypopharynx; two pairs of wings, derived from outgrowths of the body wall (unlike any vertebrate wings); and three pairs of walking legs.

21. Insect Body Plan
Thorax usually has three pairs of legs and one or two pairs of wings
Abdomen contains most internal organs and specialized structure for reproduction
Three-part gut
Malpighian tubules attach to midgut and serve in elimination of wastes

22. Insect Diversity The only winged invertebrates
More than 800,000 known species
Most successful species are small in size and have a great reproductive capacity

23. yellow fever mosquito Aedes aegypti

24. black-and-yellow argiope Argiope aurantia redlegged grasshopper Melanoplus femurrubrum

25. band-winged grasshoppers Oedipodinae

27. Class Chilopoda (centipedes)
Centipedes are uniramian arthropods whose bodies are made up of a chain of many (up to 177) flattened segments, each except the one behind the head and last two bearing a single pair of appendages (legs). The appendages of the first body segment have been modified to form large, poisonous fangs that are used to capture prey. The bite of a large centipede, however, can be painful to an adult and dangerous to a small child.

28. Millipedes and Centipedes
Segmented bodies with many legs
Millipedes
Two pairs of legs per “segment”
Scavengers
Centipedes
Flattened, with one pair of legs per segment
Predators

30. Class Diplopoda (millipedes)
Like centipedes, millipedes have bodies that are made up of numerous segments. The first four thoracic segments each bear a single pair of legs, but the following abdominal segments all have two pairs. Millipedes lack poisonous fangs and do not bite; rather, to discourage predators they roll into a defensive ball and many emit poisonous or foul-smelling substances.

31. Narceus americanus