lab 9

Question 1

Lophotrochozoan

Answer 1

• triploblastic
• one of the protosomes (along with ecdysozoans)
• all have bilateral symetry (lead to cephalization = center of nervous sytem at head)
• classified by presence of trocophore (larval stage) or a lophophore (tuft-like feeding structure)

Question 2

coelem

• what is it?
• what are the 3 ways to describe animals based on it?

Answer 2

• internal body cavity that devolops from mesoderm in protosomes
• Acoelomate = no enclosed body cavite (platyhelminthes and nemertea)
• pseudocoelomate = hae body cavities but no mesoderm lining (mesenteries) –> nematoda and rotifera
• coelomate = animals with body cavity lined with mesoderm tissues (molluska, annelida, arthropoda, echinodermata, chordata)

Question 3

coelem pros

Answer 3

• greater organ complexity
• allows movement w/o compression of organs
• hydrostatic skeleton
• shock absorbent

Question 4

coelom development

Answer 4

• begins during gastrula stage
• developing digestive tube forms pouch called archenteron
• Protosomes form coelom w/ schizocoely –> mesoderm splits into visceral and parietal layers and the space in b/t is the coelom
• Deuterostomes form coeloms w/ enterocoely –> mesoderm buds from walls of archenteron and hollows (forms from endoderm)

Question 5

Circulatory system

Answer 5

• some lack one, most have open, few have closed
• open requires less energy than closed
• open: hemolymph (blood+lymph) is pumped into hemocoels where it bathes organs and returns to heart thru ostia —> open ended vessels (found in arthropods and most mollusks
• closed: blood circulated uniderectionally from heart around body and back to heart–> capillaries, arteries, veins–> distinct separation of blood and tissue fluid–> all vertebrates and some invertebrates (cephalopods and annelids)

Question 6

Lophotrochozoan phyla

Answer 6

flatworms
rotifers
annelids
mollusks

bryozoans
brachiopods
phronids
ribbon worms

Question 7

Rotifera

Answer 7

-triploblastic pseudocoelomates
-“rotifera” = wheel –> crown of cilia draw in prey –> “corona”
-same size as some unicellular protists
-complex internal anatomy
mouth with mastax (jaw-like thing)
complete digestive tract
well developed excretory system
ocellus = light sensing eye spot

Question 8

Platyhelminthes (flatworms)

Answer 8

• 4 classes: turbellaria, monogenea(don’t care), trematoda, cestoidea
• triploblastic acoelomates
• 2 way digetive tract (w/ pharynx and gastrovascular cavity)
• no circulatory system or respiratory organs
• gas exchange thru diffusion
• aquatic or terrestrial
• free living or parasitic

Question 9

Turbellaria

Answer 9

• class of platyhelminthes
• common name = plaaria
• most are free living (non-parasitic) and marine
• bottom dwellers
• predatory or scavengers
• ciliated body surfaces

Question 10

trematoda

Answer 10

• class of plaryhelminthes
• called “flukes”
• obligate parasites w/ 2 hosts
• attach to host with suckers
• intermediate usually gastropod
• final host is often vertebrate, but can be plant
• clonorchis = human liver fluke

Question 11

cestoidea

Answer 11

• class of platyhelminthes
• tapeworms
• internal parasites (endoparasitic)
• vertebrate hosts’ guts
• no mouth or digestive tract
• scolex with hooks and suckers
• strobila = body
• proglottids = body segments –> each contains complete, sexually mature reproductive system

Question 12

annelida

Answer 12

• 3 classes: polychaetes (mostly marine), terrestrial earthworms, and freshwater leeches
• coelomates –> fluid filled coeom allowing hydrostatic movement surrounded by circular and longitudinal muscles
• metamerism (segmentation) –> each segment has own excretory, nervous, and circulatory system –> coupled with coeom, creates hydrostatic skeleton
• stae = external bristles

Question 13

oligochaeta

Answer 13

• class of annelida
• earthworm
• terrestrial
• hermaphroditic, but out-cross
• movement thru alternating contractions of longitudinal and circular muscles
• clitellum = excretes a chitnous band that collects sperm and its own eggs to form an externally shed cocoon where fertilization takes place

Question 14

mollusca

Answer 14

• 7 classes: gastropoda, bivalvia, aplacophora, monoplacaphora, polyplacaphora, scaphopoda, cephalopoda
• mostly marine
• soft bodies
• no segmentation
• coelomates
• CaCO3 shells
• visceral mass = concentration of internal organs
• mantle = dorsal body wall of all mollusks (functions in respiration and motion)
• muscular foot = muscular surface on ventral side (functions in locomotion and feeding)

Question 15

cephalopod

Answer 15

• class of mollusca
• octopuses, squids, nautiluses, cuttlefish
• fast ocean predators
• highly developed nervous system with fused ganglia (brain)

efficient circulatory and gas exchange systems:

• only mollusk class with closed circulatory
• dual pumping mechanisms = 2 branchial (gill) hearts send blood to gills for gas exchange-> blood returns from gills to systemic heart where its pumped to the rest of the body
• fascilitates pretty high metabolic rates and supports active muscles