Animal Diversity 3. jointed appendages ventral nervous system hemocoel. - marine

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1 Animal Diversity 3 Lab Goals To learn the bauplan (body plan) and identifying characteristics of the phyla Arthrodopa, Echinodermata, and Chordata along with the main subphyla and classes. Include, in your lab notebook, labeled drawings of each specimen provided. Arthropoda Terms biramous book gills book lungs calcareous chelicerae cirri ecdysis hemocoel mandible maxilla opisthosoma prosoma tagmatization telson uniramous Characteristics bilateral symmetry tagmatization exoskeleton jointed appendages ventral nervous system hemocoel ecdysis growth Diversity Subphylum: Chelicerata - two tagma (prosoma, opisthosoma) - first pair of appendages are chelicerae Class: Merostomata (horseshoe crabs) - book gills - long telson - marine Class: Arachnida (spiders, scorpions, ticks, mites, harvestmen, etc.) - book lungs &/or tracheae - mostly terrestrial - four pairs of walking legs Subphylum: Crustacea - two pairs of antennae - one pair of mandibles - two pairs of maxillae - biramous appendages - mostly aquatic Class: Branchiopoda (brine shrimp, fairy shrimp, etc.) - flattened appendages - minimal tagmosis - appendages often uniform in appearance - mostly freshwater Class: Malacostraca (lobster, crayfish, crabs, shrimp, isopods, etc.) - carapace covering thorax in most - well differentiated appendages - mostly marine or freshwater Class: Maxillopoda (barnacles, copepods)

2 - abdomen often reduced - abdomen often without appendages - thoracic segments fused with head - cirri (feeding appendages, barnacles only) - calcareous plates (barnacles only) Subphylum: Hexapoda (insects, etc.) - head, thorax & abdomen tagma - uniramous appendages - five pairs of cephalic appendages - three pairs of thoracic appendages Subphylum: Myriapoda (millipedes, centipedes) - head and trunk tagma - numerous walking legs along trunk - four pairs of head appendages - terrestrial Dissection You will dissect a grasshopper, an insect (Hexapoda), to observe external and internal morphology. Using figure 1 and your textbook, locate all external anatomical features prior to dissecting. Determine if your specimen is a male or female. If you have a male, be certain to find the ovipositors on a female grasshopper from another group. External Anatomy abdomen antennae compound eyes head hypopharynx labium mandibles maxillae ovipositors (female only) spiracles thorax wings Figure 1. External anatomy of a grasshopper. Modified from Brusca and Brusca, 1990, Invertebrates, Sinauer Associates.

3 Using scissors, remove the exoskeleton by first taking off the wings and then cutting through the exoskeleton, beginning at the posterior end and just above the spiracles, cut two lateral lines toward the head. Carefully remove the dorsal exoskeleton and use pins to hold open the grasshopper. Using figure 2, locate most of the internal anatomy and then push the digestive tract aside to locate the ventral nerve cords. Internal Anatomy crop gastric cecae intestine malpighian tubules ventral nerve cords Figure 2. Internal anatomy of a grasshopper. From Miller and Harley, 1990, Zoology, McGraw Hill. Specimens horseshoe crab (Merostomata), wet scorpion (Arachnida), wet tick (Arachnida), wet (2) spider (Arachnida), wet fairy shrimp (Branchiopoda), wet lobster (Malacostraca), wet crab (Malacostraca), dry crab, male & female (Malacostraca), wet mole crab (Malacostraca), wet hermit crab (Malacostraca), wet isopod (Malacostraca), wet barnacle, (Maxillopoda), wet barnacle, no plates (Maxillopoda), wet millipede (Myriapoda), wet centipede (Myriapoda), wet house fly, (Hexapoda), acrylic potato bug (Hexapoda), wet cockroach, (Hexapoda), acrylic dragonfly (Hexapoda), wet

4 Echinodermata Terms ambulacral groove ampulla central disk cirri madreporite pedicellaria Characteristics pentaradial symmetry water-vascular system Diversity Class: Crinoidea (sea lilies) - most are sessile - stock or cirri for attachment Class: Asteroidea (sea stars) - rays blend with central disc - ambulacral grooves open Class: Ophiuroidea (brittle stars, basket stars) - rays set off of central disc - ambulacral grooves closed Class: Echinoidea (sea urchins, sand dollars) - no rays - ambulacral grooves closed Class: Holothuroidea (sea cucumbers) - no rays - fleshy body Specimens sea lily (Crinoidea), acrylic bat star (Asteroidea), dry ocre star (Asteroidea), dry sunflower star (Asteroidea), dry sea star (Asteroidea), wet in acrylic brittle star (Ophiuroidea), wet basket star (Ophiuroidea), wet radial canal ring canal spine test tube feet water-vascular system calcareous endoskeleton marine - arms may branch - suction disks on tube feet - pedicellaria - no suction disks on tube feet - moveable spines - fused skeleton as test - oral-aboral elongation - tentacles around mouth sand dollar (Echinoidea), dry sand dollar, no spines (Echinoidea), dry sea urchin, no spines (Echinoidea), dry sea urchin (Echinoidea), acrylic sand dollar (Echinoidea), acrylic sea cucumber (Holothuroidea), wet

5 Dissection You will dissect a sea star to observe external and internal morphology. Using figure 3, locate all external anatomical features prior to dissecting. External Anatomy ambulacral groove arm central disc madreporite mouth pedicellariae tube feet Carefully cut a large section of the endoskeleton across and along the aboral surface of an arm and another section around the aboral surface of the central disk. Locate the internal anatomy structures using figure 3. Internal Anatomy ampullae radial canal ring canal stomach digestive gland gonad Figure 3. External and internal anatomy of a sea star (Asterias vulgaris). (a) Aboral surface. (b) Oral surface. (c) Internal structures shown with part of the endoskeleton removed. From Castro and Huber, 2007, Marine Biology, McGraw Hill.

6 Chordata Terms notochord pharyngeal slits Characteristics bilateral symmetry dorsal hollow nerve cord notochord postanal tail tunic pharyngeal slits postanal tail Diversity Subphylum: Urochordata (sea squirts) - notochord, nerve cord, and postanal tail absent in adults - most adults are sessile adults - tunic - marine Subphylum: Cephalochordata (amphioxus) - laterally compressed - all chordate characteristics persist through life - marine, freshwater, and terrestrial Subphylum: Craniata (hagfishes, vertebrates) classes covered in future labs Specimens sea squirt (Urochordata), acrylic sea squirt (Urochordata), wet lancelet (Cephalochordata), wet lancelet (Cephalochordata), acrylic * Wet specimens are preserved in a jar of alcohol. * Dry specimens are not preserved in a jar of alcohol.