Dorsal simple eye, compound eyes (paired), prosoma, opisthosoma (cephalothorax and abdomen), movable spines, telson (tail)

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1 Phylum Arthropoda Subphylum Cheliceriformes Class Celicerata Subclass Merostomata = smallest living group of chelicerates, only 4 species are known, most ancient arthropods (Ordovician) Limulus polyphemus the horseshoe crab Specimens for identification of external characteristics Dorsal simple eye, compound eyes (paired), prosoma, opisthosoma (cephalothorax and abdomen), movable spines, telson (tail) Ventral chelicerae, pedipalps, chelate legs (4 pairs), gnathobases (basal segment of leg, heavily spined), genital operculum, book gills, anus => External gender specific differentiation??? Subclass Arachnida Latrodectus mactans black widow spider Aphonopelma sp. tarantula Paruroctonus sp. American scorpion => can you find some of the characteristics described for Limulus polyphemus in any of these animals? i.e. prosoma, opistosoma, chelicerae, pedipalps, walking legs (how many pairs)

2 => What are the differences between the arachnids and the merostomata? Differences in structures and functions of specific body parts/ segments? How do those differences reflect the lifestyle these animals lead? Ticks (slides to observe body and mouth parts) Gnathosoma (capitulum), idiosoma, scutum with opening to lung lamellae, walking legs Walking legs coax, trochanter, femur, patella, tibia, metatarsus, tarsus (may have terminal claw) Mites and Chiggers In all environments, even collected in air (dustmites?) Can you find prosoma and opisthosoma? Body and tactile setae? Pedipalps and chelicerae? Do mites have eyes? => How does the mite structure different from the other chelicherates? Phylum Arthropoda Subphylum Uniramia Class Insecta Order Orthoptera crickets, grasshoppers, locusts (20,000 sp) Romalea microptera lubber grasshopper Preserved specimens for dissection

3 External body divided into 3 tagmata (how many do the chelicerates have?): head, thorax and abdomen; head = divided into frons, clypeus and labrum, antennae (how many pairs), paired compound eyes, three simple eyes (dissection microscope), gena (cheek), mandible, maxilla, labium (submentum, mentum, ligula), labial palp, maxillary palp; thorax = separated into three parts (I, II and III; or prothorax, mesothorax and metathorax), spiracles (on what parts), front and hind wings (front wings = wing covers; wing veins visible) three pairs of walking legs; abdomen = separated into 11 parts (1-11 sclerites divided into tergite and sternite, which is which), tympanum, spiracles, circus, ovipostor (what sex); legs = coax, trochanter, femur, tibia, tarsus, (pretarsus on jumping legs) Internal dorsal diaphragm (separates dorsal and ventral pericardial sinus), dorsal heart (inconspicuous, shape?), silvery tracheae (leading to?), segmental muscles, air sacs (large white structures, anterior abdomen and thorax), flight muscles (underneath sclerites, what part of the body?), fat bodies (yellow, throughout hemocoel, but most prevalent in abdomen), gut (underneath fat bodies) = esophagus, crop, midgut with digestive caecae and some Malphigian tubules (function), intestine and rectum (covered by reproductive system), ventral nerve cord (with thoraic and abdominal ganglia (what do they look like?), brain (optional, protected by sclerotonized cranium) => don t worry about the reproductive structures, but be aware whether you are looking at a male or female Romalea

4 Periplaneta americana American cockroach External head = (frons, clypeus, labrum), compound eyes, flagellum, maxillary and labial palps; thorax = prothorax always visible (meso and metathorax obscured by wings), 3 pairs of legs, wings (how many pairs?); abdomen = separated into 11 segments (tergite and sternite with articular membrane, segment 11 and 10 fused); circus; spiracles Order Odonata = dragonflies large compound eyes, two large pairs of veined wings, abdomen slender and elongate (10 segments) => lifestyle? Order Hemiptera = true bugs piercing mouthparts (beak), flat wings and dorsum => examples? What are some Order Homoptera = cicadas, scale insects etc. example Tibicen canicularis dog day cicada piercing mouthparts for a beak (who do they bite), 2 pairs of membranous wings (usually held tent like over abdomen), hindlegs adapted for jumping Order Diptera = true flies, mosquitoes 1 pair of membranous wings (adults), head large, large compound eyes, mouthparts adapted for lifestyle, abdomen primitively 11-segmented

5 Order Hymenoptera = wasps, bees and ants elongated, modified mouthparts (lifestyle?), two pairs of membranous, body sometimes covered in hairs