Ch. 33: Invertebrates Flashcards
Sponges have been traditionally considered as the ..
Basal animal group
Basal animal group, however,
recent data suggest that a – bilateral organism is more likely basal and
– Ctenophora has been tentatively placed as the basal animal group
Cnidarians are an
Ancient phylum of radially symmetrical and diploblastic animals
Lophotrochozoans
- A clade identified by molecular data
- Have the widest range of animal body forms
Ecdysozoans
The most species-rich animal group
Echinoderms and Chordates are
Deuterostomes
Porifera
- Asymmetric
- Lack Tissues
- Cellular-level of organization
- Needs: O2, nutrients (in) and CO2, waste (out)
- Porocytes: form tube that water can go through
- Choanocytes: currents …
- Pinacocytes (epidermis): epidermal cells
- Amoebocytes
- Meshyl
- Thin wall around open space (3 levels)
- Low metabolic rate
- High SA/V
- Main ∆c = bulk flow
- Sessile organisms
- Crypsis
Porocytes
form tube that water can go through
Choanocytes
currents ??
Pinacocytes
in epidermis
- Epidermal cells
Amoebocytes
d
Sessile Organisms
Gemule
Gemule
if freshwater, can form spore-like structures that could …
- some land on hermit crabs
Crypsis
the ability of an animal to avoid observation or detection by other animals
- i.e. camouflage
Crypsis
the ability of an animal to avoid observation or detection by other animals
- i.e. camouflage
Cnidaria
- named after cnidocytes
- Diploblastic, tissue level
- Radial Symmetry
- Nerve Net (only “system”)
- Myoepithelial (muscle)
- Epidermis (Ectoderm)
- Gastrodermis (endoderm)
- Mesoglea (gelatinous substance)
Cnidocyte
cells with nematocyst
Cnidocil
sensitive to touch
- mechanoreceptor protein
- can change/ permeability to water
2 body forms of Cnidaria
1) polyp
2) medusa
- Both have epidermis and gastrodermis (cover gastrovascular cavity)
Polyp
- tentacles are thicker
- sessile form
Medusa
d
Diverticula
medusa
“sac”
Nervous system of cnidaria
movement
coordinating
spacial ?
Metabolic Requirements for Animal Life
1) Oxygen (O2) in and CO2 out
2) Nutrients in
3) Waste out => nitrogenous waste (one of three forms: NH3 (ammonia), Urea, Uric Acid
4) Water/Salt balance (osmotic)
5)
Metabolic Requirements for Animal Life
1) Oxygen (O2) in and CO2 out
2) Nutrients in
3) Waste out => nitrogenous waste (one of three forms: NH3 (ammonia), Urea, Uric Acid
4) Water/Salt balance (osmotic)
5) Central control of cell/tissue function
=> (neurons) via nervous system via endocrine system
Phylum Ctenophors (comb jelly)
- named after ctene (comb)
- “Comb” rows of cilia used for locomotion
- Radial symmetry
- Diploblastic
- Epidermis
- Mesoglea
- Gastrodermis
- GVC (gastrovascular cavity)
- No cnidocyte; yes to colloblast (sticky (ensnare prey)
- complete digestive system
- Large SA/V ; Fiele’s Law
Bilartaria
- Bilateral Symmetry
- Cephalization (making a head)
=> concentration of sensory organs/nerves at one end
Lophotrochozoa (2 groups)
1) Lophophorates
2) Trochozoa
- lophophore: feeding structure
- trochophore larvae
- animal
Ecdysozoa
- ecdysis: mold/shed cuticles (thick part of epidermis/ exoskeleton)
- animal
Platyhelminthes
flatworms
- dorsal-ventral flattening
- Can be free-living or parasitic
- Bilateral
- Triploblastic (3 layers)
- Acoelomate
- can be parasitic (Tapeworm and flukes) or free-living (Planaria/Dugesia)
Triploblastic layers of Platyhelminthes
- ectoderm: epidermis/nerve
- Mesoderm: parenchyma (C.T., muscle)
- Endoderm: gut
Dioecious
separate sexes
Monoecious
hermaphroditic
self-fertilization
Trematoda
Flukes: 2 types
1) Clonorchis sinensis (Chinese liver fluke): human and two intermediate hosts
2) Schistosomes: “blood fluke”
infection: schistosomiasis/
live in veins/ burrow in human skin
Clonorchis sinensis life cycle
- eggs go into snail
- go into fish muscle
- humans eat fish
- lives in gull bladder or bile duct
- dominate host: human
- intermediate host: snail, fish
Schistosomes life cycle
- burrow into human skin
- ciliated larva go into snail
- motile larva will burrow into human skin
- dominate host: human
- intermediate host: snail
Planaria can be cut
- up to 10 transverse cuts = 10 planar
- cut closer to head => faster regeneration
- the orientation of actin cytoskeleton can effect rate/type of regeneration
Phylum Rotifera
- pseudocoelomate
- complete digestive tract
- wheel-animals
- primarily freshwater but some marine
- rarely see males
- have toes: suspension feeders
Corona
- wheel organ found in the Phylum Rotifera
- jaws (mastea): structure can close
- Circulatory crelonic fluid
- Pedal glands
Rotifera reproduce
through parthenogenesis: development of unfertilized egg (haploid)
Lophophore vs Trochophore
Lophophore:
- U-shaped tentacle
- Feeding apparatus
- All marine
- i.e. ectoprocts (sea mat) branchpods
Trochophore: - Ciliated larvae w/ complete digestive system - Ciliated: => apical tuft => equatorial band => Complete digestive system => Respiratory/circulatory organs
Phylum Mollusca
- adaptive radiation into a variety of riches
- larger
- more complex, more systems
- Tripartite body plan: mantle, visceral mass, foot
Tripartite body plan of Mollusca
- Mantle: may secrete a shell (always have)
- Visceral Mass: organs and coelom and hemocoelom
- Foot (muscular): heart and kidneys (nephridium), gonads
Mollusca hemocoel
- hemolymph: a fluid filled cavity
- suspended within a gastrointestinal tract
Mollusca Mantle Cavity
air space (acts as simple lung)
or gills present (aquatic sp)
Mollusca Cardiovascular System
Open: hemolymph is not contained in vessels at all times
organs bathed in hemolymph directly
Mollusca digestive system
Complete
- Mouth: radula: stiff-ribbon-like appendage with chitin => scraping
- Pharynx => stomach <=> digestive glands (pyloric ceca) acts like both a liver and pancreas and absorptive organ
stomach => intestine => anus
Mollusca Respiratory
“lung” (simple) = mantle cavity
gills
Mollusca Nervous System
- Circumpharyngeal ganglion (“brain”)
- Ventral nerve cords
- Other smaller ganglia in visceral mass
Class Gastropod
Phylum Mollusca
- have torsion
- visceral mass turns
Class Bivalvia
Phylum Mollusca
- Ctenidia: ciliated; capture food/ respiratory/ gills
Class Cephalopoda
Phylum Mollusca
- body plan modified for locomotion/feeding
- Closed circulatory system
- Great Vision
- i.e. Nautilus: can add/lose air
- Octopus/Squid: can change color for different reasons
- > Octopus: based on moods/ communication
- > Squid: mating, terrestrial (cuttlefish)
Phylum Annelida
- coelomates with metamerism
Metamerism
a serial (repetition) row of similar body parts along the length of an animal
Coelomate
Septa divide coelom into compartments associated with block of muscle
why a metamerism
- great increase in muscle coordination
- increase types of actions possible
- adaptive radiation
Nervous system of Phylum Annelida
- circumpharyngeal ganglion
- 2 ventral nerve cords
- each metamere is independently controlled by transverse nerves
- tactile, chemosensory
Annelida Coelom
1) independently move body wall and gut
2) expansion of space for gonads and larger and more types of organs
3) (serves as a) hydrostatic skeleton (very important)
Annelida Circulatory system
- closed
- no heart, but pulsatile arteries
- Coelomic fluid: medium for diffusion to and from circularity vessels
- Hemolymph: contains some hemoglobin/ a respiratory pigment/ increase total [O2] in hemolymph
=> O2 soluble and O2 bound to pigment
