Lab 7: Protostomes

triploblastic animals 2 types

• deuterostomes

• protostomes

deuterostomes ex.

Echinodermata, Chordata, and one other phylum

protostomes ex.

2 major groups of phyla

• ecdysozoa: arthropoda, nematoda, and others

• lophotrochozoa: mollusca, annelida, bracihopoda, platyhelminthes, and many more

protostome: fate of the blastopore

embryonic blastopore becomes the mouth

deuterostome: fate of the blastopore

embryonic blastopore becomes the anus

protostome: coelem formation

coelom formation is schizocoelous

• the body cavity forms when the mesodermal tissue "splits”

deuterostome

coelom formation is enterocoelous

• the body cavity forms when pockets of the primitive gut (archenteron) bud off

protostome: cell fate

determinate: cells are pre-programmed

deuterostome

indeterminate: cells are stem cells

ecdysozoa

one of the two major branches of the protostomes

• ecdysis = molting

• triploblastic

• bilaterally symmetrical

• more ecydsozoan species than all other animals combined

true or false. ecydysozoa are triploblastic

true

true or false. ecdysozoa are asymmetrical

false. ecdysozoa are bilaterally symmetrical

phylum nematoda

nemata or roundworms

• pseudocoelomate

• complete digestive tract

• longitudinal muscles only (whiplike movement)

• dioecious (separate sexes usually)

phylum nematoda

Ascaris, Trichinella, vinegar eel

phylum nematoda: vinegar eels

• turbatrix aceti

• free living

• feed on bacteria & yeast

phylum arthropoda

• jointed appendages

• segmented body

• exoskeleton composed of chitin

• open circulatory system

• 3 major groups: myriapoda, chelicerata, and pancrustacea

phylum arthropoda: subphylum myriapoda

• single pair of antennae

• single pair simple ocelli (“eyes”)

• 3 pairs of modified appendages for mouthparts

• breathe w/ spiracles and tracheae

• centipedes

• millipedes

phylum arthropoda: subphylum myriapoda: centipedes

• carnivorous

• 1 pair of legs per segment

• possess poison fangs

phylum arthropoda: subphylum myriapoda: millipedes

• herbivorous

• 2 pair of legs per segment: each segment is 2 segments fused together

phylum arthropoda: subphylum chelicerata

• possess chelicerae

  • used as pincers or fangs

• 2 body regions

  • cephalothroax & abdomens

• 6 pairs of appendages

  • 4 pairs of legs, 1 set of chelicerae, 1 set of pedipalps

• breathe using gills or book lungs

phylum arthropoda: subphylum chelicerata: 2 body regions

cephalothorax and abdomen

phylum arthropoda: subphylum chelicerata: possess chelicerae

used as pincers or fangs

phylum arthropoda: subphylum chelicerata: 6 pairs of appendages

4 pairs of legs, 1 set of chelicerae, 1 set of pedipalps

phylum arhthropoda: pancrustacea

• hexapoda and crustacea are more closely related than any other two groups within the arthropoda

• molecular studies suggest this is a monophyletic clade

• many synapomorphies between hexapods and crustaceans

phylum arhthropoda: pancrustacea: synapomorphies between hexapods and crustaceans

• heavily segmented

• compound eyes

• well-developed mandibles

• 3 clearly distinguished body regions: head, thorax, and abdomen

phylum arhthropoda: pancrustacea: subphylum hexapoda

insects and related taxa

• 3 pairs of walking legs

• wings

  • usually 2 pairs

  • the only invertebrates to have evolved true flight

• also have special feeding appendages and sensory organs

• breathe using well-developed spiracles and tracheae

phylum arhthropoda: pancrustacea: subphylum crustacea

• most marine, some freshwater, a few terrestrial

• 2 pairs of sensory antennae

• each body segment has 2 appendages: antennae, mouth parts, cheliped, legs, swimmerets, and tail fins

• >3 pairs walking legs

• biramous (branched) appendages

• gills or “branchiostegal lungs” for respiration

phylum arhthropoda: pancrustacea: subphylum crustacea: how many sensory atennae

2

phylum arhthropoda: pancrustacea: subphylum crustacea: body segments

each body segments has 2 appendages

• antennae, mouth parts, cheliped, legs, swimmerets, and tail fins

phylum arhthropoda: pancrustacea: subphylum crustacea: what is used for respiration?

gills or “branchiostegal lungs”

phylum arhthropoda: lophotrochozoans

aka spiralia: the other major branch of protostomes

• triploblastic & bilaterally symmetrical

• very diverse clade w/ around 10-15 phyla

• 3 defining features found in many, but not in all

phylum arhthropoda: lophotrochozoans: 3 defining features found in many, but not in all

• many have spiral cell division

• lophophore (lophophorates) crown of ciliated tentacles that surround the mouth used for feeding

• trochophore (trochozoans) the larval stage of annelids and mollusks, some others

phylum platyhelminthes: flatworms

• flat bodies

• aceoelomate

• hermaphroditic

• ladder-like (simple) nervous system, exhibit primitive organ systems

• first example of cephalization (development of a head) in the fossil record

phylum platyhelminthes: planarians

• have protonephridia (flame cells) for osmoregulation

• incomplete digestive tract

phylum platyhelminthes: rhabditophora

planarians

• free-living predators or scavengers

• have protonephridia (flame cells) used for osmoregulation

• “eyespots” - photoreceptive neurons (aka ocelli)

• protrusible pharyx used for eating and voiding feces

  • incomplete digestive tract

phylum platyhelminthes: rhabditophora: protrusible pharyx

used for eating and voiding feces

• incomplete digestive tract

phylum platyhelminthes: rhabditophora: eyespots

photoreceptive neurons (aka ocelli)

phylum platyhelminthes: rhabditophora: class cestoda

tapeworms

• internal parasites

• definitive host is a vertebrate

• no digestive system

• attachment organ called scolex

  • no its head, doesn’t have one :(

• proglottids

phylum platyhelminthes: rhabditophora: class cestoda: proglottids

reproductive segments, break off end of worm when fully mature

phylum platyhelminthes: rhabditophora: class cestoda: attachment organ

called a scolex (not its head)

phylum mollusca

chiton, snails, clams, and cephalopods

• mostly marine

• have a trochophore larval stage

• 4 major clades: Polyplacophora, Gastropoda, Bivalvia, Cephalopoda

phylum mollusca: characteristics

foot: movement and food capture

visceral mass: contains the organs

mantle: secretes shell (usually)

radula: scrapes food, found in 2 of the major clades

open circulatory system: no blood vessels except heart, found in 3 of major clades

phylum mollusca: class polyplacophora

chitons

• segmented shell (8 plates) does NOT represent true segmentation

• scrapes algae off rocks w/ a radula

phylum mollusca: class polyplacophora: how many plats does the segmented shell have?

8 plates, does NOT represent

phylum mollusca: class gastropoda

slugs, snails, and nudibranchs

• some exhibit torsion: 180 degree rotation of the visceral mass

• some have shells many snails have radulas

phylum mollusca: class gastropoda: torsion

180 degree rotation of the visceral mass

phylum mollusca: class bivalvia

clams, oysters, scallops, and mussels

• animals contained within 2 hinged valves

• incurrent and excurrent siphons

• 4 oversized gills for filter feeding

phylum mollusca: class bivalvia: how many oversized gills?

4, for filter feeding

phylum mollusca: class cephalopoda

chambered nautilus, squid, and octopi

• all are predators

• the most advanced invertebrates

• chromatophores

• octopi have 8 arms; squid also have 8 arms AND 2 longer tentacles

• notice hooks on tentacles used for grabbing prey

• pen is remnant of shell, is internal - found in squid

• octopi have no pen

• all octopi have venomous bites

phylum mollusca: class cephalopoda: the most advanced invertebrates

1. closed circulatory system w/ 3 hearts - dual circuit circulation

2. well-developed eyes

3. most intelligent invertebrates

phylum mollusca: class cephalopoda: chromatophores

pigmented cells that help these animals change color: communication and camouflage

phylum mollusca: class cephalopoda: pen

remnant of shell, is internal - found in squid

phylum brachiopoda: lophophorates

• sessile

• coelomate

• lophophore and pedicle present

• very abundant in fossil record (paleozoic era), now only about 350 species remain

• are NOT mollusks

• shells of calcite (CaCO3) & proteins, around body

• 2 classes: articulata & inarticulata

phylum brachiopoda: lophophorates: true or false. lophophore and pedicle are present.

true

phylum brachiopoda: lophophorates: true or false, they are mollusks

false. not mollusks

phylum brachiopoda: lophophorates: shells

shells of calcite (CaCO2) & protein, around body

phylum brachiopoda: lophophorates: 2 classes

articulata & inarticulata

phylum annelida: segmented worms characteristics

• truly segmented body (divded by septa)

• closed circulatory system

  • convergent w/ vertebrates & cephalopods

• have a trochophore larval stage

  • shared w/ Mollusca and a few other phyla

phylum annelida: segmented worms: 2 major clades

• errantia: free-living marine sand worms

• sedentaria: mostly sessile marine worms, earthworm and fres

phylum annelida: class errantia: well-developed sense organs

antennae and eyes

phylum annelida: class errantia: true or false. class errantia are free-living mobile marine worms

true

phylum annelida: class errantia: possess fleshy _______ with tiny, chitinous ______ aka ____ (bristles) on each segment

parapodia, chaetae, setae

phylum annelida: class sedentaria

sedentary marine tubeworms, earthworms, and leeches

• posses few to no setae (bristles) and (often) a clitellum

  • gives them together while mating

  • secretes cocoon around eggs

phylum annelida: class sedentaria: function of the few to no setae (bristles) and clitellum

• glues them together while mating

• secretes cocoons around eggs

earthworm cross section

• body wall

• intestinal lumen

• intestinal wall

• longitudinal muscle layer

crayfish anatomy

antennae, antennules, compound eyes, chelipeds, rostrum, swimmerets, head, thorax, abdomen, tail, walking legs, carapace, inner and outer jaws

insect anatomy

compound eyes, antennae, head, thorax, abdomen, tympanic membrane, spiracles, wings, walking legs

earthworm dissection

pharynx, gizzard, intestine, dorsal blood vessel, crop, septum

squid dissection

suckers, arms, tentacles, mouth, eyes, siphon, gills, mantle, pen and ink sac