Lab 8: Lab 8: Animals II: Non-molting and Animals II: Non-molting and

Molting ProtostomesMolting Protostomes

• Non-molting

• unsegmented

• muscular foot (may be highly modified)

• mantle – membrane present in all; in most, secretes and maintains one or two calcerous valves (shells)

• most have a radula (rasping tongue with chitinous teeth)

Phylum Mollusca - Mollusks

• diverse group, over 100,000 living species (2nd ranking in number among animal phyla)

• of 7 classes, 4 classes covered in lab:

• Polyplacophora (chitons)

• Gastropoda (gastropods) – snails, slugs, and nudibranchs (sea slugs)

• Bivalvia (bivalves) – scallops, oysters, clams, etc.

• Cephalopoda (cephalopods) – octopuses, squid, cuttlefish, etc.

Phylum Mollusca - Mollusks

• Video: The Shape of Life: Episode 6 – Survival Game (Molluscs)

• body plan

• radula

• octopus camouflage

Phylum Mollusca - Mollusks

• examine the preserved specimens in the mollusk box and on display, note the following:

• Polyplacophora – chiton (display only): • gills• mantle• foot

Task A-1: Phylum Mollusca

• examine the preserved specimens in the mollusk box and on display, note the following:

• Gastropoda – snail and slug:• coiled valve (snail) or no valve (slug)• broad, flat foot

Task A-1: Phylum Mollusca

• examine the preserved specimens, note the following:

• Bivalvia – clam:

Task A-1: Phylum Mollusca

• examine the preserved specimens, note the following:

• Cephalopoda – squid:

• muscular foot with tentacles (with suction discs)

• thick mantle but no external shell (true for most cephalopods)

• excurrent siphon (for jet propulsion)

• large eyes

Task A-1: Phylum Mollusca

• molting (ecdysis) – periodic shedding of protective cuticle so that organism can grow or change

• pseudocoelomate

• complete digestive system

• dioecious

• longitudinal muscles for movement

• many are free-living, but many are parasites

• very common in soil

Phylum Nematoda – roundworms

• examine the preserved specimens in the Nematoda box

• prepare and examine a slide with live vinegar eels; note their movement, powered by longitudinal muscles

• examine Ascaris cross section slide; note structures from figure 8-3

Task B-1: Phylum Nematoda

• “joint-foot” – jointed appendages

• segmented – often with some fusing and distinctive regions (details later); very distinct cephalization

• exoskeleton containing chitin; used for protection, and for muscle attachments

• molting (ecdysis) – shedding of exoskeleton for growth; new exoskeleton later hardens

Phylum Arthropoda – arthropods

• very diverse group and successful group

• over 1 million named species, by far the most species of any phylum (in fact, 2/3 of ALL named species)

• estimates are as high as 30 million living species unnamed

• most of the species (well over half) are insects

Phylum Arthropoda – arthropods

• focus on both subphyla and classes for tests

• 4 subphyla, 6 selected classes to cover

• Subphylum Cheliceriformes

• Subphylum Myriapoda

• Subphylum Crustacea

• Subphylum Hexapoda

Phylum Arthropoda – arthropods

• body plan: cephalothorax and abdomen• on cephalothorax, starting at anterior end:• paired chelicerae• paired pedipalps• 4 pairs of legs

• selected classes:• Merostomata – horseshoe crab• Arachnida – spiders, scorpions, mites, ticks, etc.

Subphylum CheliceriformesSubphylum Cheliceriformes

• Body plan: head and multisegmented trunk

• on head:

• one pair of antennae

• paired mandibles

• Legs on trunk (either one or two per segment, depending on class)

• appendages are uniramous (unbranched)

• most have tracheal respiratory system

Subphylum MyriapodaSubphylum Myriapoda

• Diplopoda (millipedes)

• two pairs of legs per trunk segment

• Chilopoda (centipedes)

• one pair of legs per trunk segment

• poison claws on trunk segment nearest the head

Subphylum MyriapodaSubphylum Myriapoda

• One class (also called Crustacea)

• barnacles, crayfish, crabs, lobsters, shrimp, etc.

• on cephalothorax, starting at anterior end:

Subphylum CrustaceaSubphylum Crustacea

• two pairs of antennae (unique feature)

• paired mandibles (jaws)

• most then have 5 pairs of chelate appendages (pincher-like)

swimmerets

• appendages are biramous (two-branched; another unique feature)

Subphylum CrustaceaSubphylum Crustacea

• Hexapoda – “six feet”

• One class to worry about: Insecta

• Body plan: head, thorax, and abdomen

• On head: one pair of antennae

• On head: paired mandibles

• On thorax: three pairs of legs

• On thorax: often two pairs of wings

• appendages are uniramous (unbranched)

• most have tracheal respiratory system

Subphylum HexapodaSubphylum Hexapoda

• arthropod box and displays:• for all, note segmentation, head, exoskeleton, and

paired jointed appendages • items to note for each animal class (use Fig. 8-4

as a guide for structures): • Merostomata – horseshoe crab• large cephalothorax (from dorsal and ventral

views)• chelicerae, pedipalps, and legs• book gills• telson

Task B-2: Phylum Arthropoda

• arthropod box:• Arachnida – garden spider• chelicerae with fangs• pedipalps (used by males in mating)• 4 pairs of legs• unsegmented abdomen with spinnerets for

making silk

Task B-2: Phylum Arthropoda

• arthropod box:

• Crustacea

• barnacle – shell and holdfast

• blue crab – chelate appendages, mouth and feeding appendages, cephalothorax, abdomen (tucked under cephalothorax)

• crayfish – chelate appendages, mouth and feeding appendages, cephalothorax, gills, abdomen with swimmerets (note biramous nature)

Task B-2: Phylum Arthropoda

• arthropod box:

• Diplopoda – millipede

• head with mandibles, short antennae

• multisegmented trunk

• two legs per segment (key to identification)

• look for evidence that each “segment” is actually a fusion of two segments

• look for spiracles

Task B-2: Phylum Arthropoda

• arthropod box:

• Chilopoda – centipede

• head with mandibles, short antennae

• multisegmented trunk

• one legs per segment (key to identification)

• poison claws derived from first leg pair

• look for spiracles

Task 3: Arthropods (Phylum Arthropoda)

• arthropod box:

• Insecta – grasshopper and walking stick

• head with antennae, mandibles, and compound eyes

• thorax with three pairs of legs (note uniramous appearance of appendages) and two pairs of wings (grasshopper)

• segmented abdomen

• spiracles on sides

• in grasshopper, note the large tympanum (eardrum) on first segment

Task B-2: Phylum Arthropoda

• arthropod slides:• tick, body louse, and water flea (Daphnia)• for each, try to identify the class based on

external features

Task B-2: Phylum Arthropoda

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