Invert. Zoology

Midterm 1

“Bauplan”

Blueprint; limit of organism

Radical symmetry

oral-aboral axis; no “behind”, slow

“perfect; symmetry

1 axis, infinite planes,

Biradial symmetry

1 axis, 2 planes; sensory structures in front, blind spots

Endoderm

outside; protective tissues, neurons

Mesoderm

Middle; circulatory, muscles

Endoderm

Inside; gut tube, liver

Diploblastic

only ectoderm & endoderm

Triploblastic

all 3 germ layers

What is a body cavity?

fluid filled space between gut and body wall

Acoelomate

filled in with solid tissues (flatworms)

Pollastocoelmate

Surrounded by muscle

Coelomate

“true” body cavity

kinds of skeletal structures

exoskeleton, endoskeleton, rigid

Hydrostatic

muscle acts against body fluid (noncompressable)

Rigid

Endo/exto skeleton; muscles act against hard skeleton (no change in shape)

“Antagonistic”

muscles; in pairs- one pull, one relax

complete gut

specialized; through

incomplete

less specialized; blind

Intracellular digestion

chemical digestion inside gut

Extracellular digestion

chemical digestion outside gut

Gut shapes

through, pouch, U-shaped

Feeding stategies

Suspension, deposit, herbivory, carnivore/ scavenging,

Open circulation

blood leaves arteries

Closed circulation

closed loop (blood never leaves vessels)

Kinds of nervous system

nerve net, nerve cord, brain/ganglia

Mechanoreceptors

feeling, grabbing

Chemoreceptors

tongue, nose, antenna, detection

Photoreceptor

light, image

Asexual reproduction

fragmentation, budding, fission, parthenogenesis

External fertilization

Spawning

Internal fertilization

Hermaohoritism

Holoblastic

complete cell division; dependent on yolk

Meroblastic

incomplete separation; embriotic

Coeloblastula

Discoblastula

Stereoblastula

Periblastula

Ingression

folding the gut

Coelum formation: Schizocoley

forms from splitting in the mesoderm

Coelum formation: Entercoely

forms from outpocketing in developing gut

Radical cleavage

echnoderms; cells divide perpendicular to embryos’ vertical axis

Spiral cleavage

mollusks; oblique cell division; creating spirals

Planktotrophic

Can eat on its own, off the bat

Lecithotropic

eat moms yolk

Indirect development

larvae may be feeding/ non-feeding, larve go through metamorphosis, R-selected

Direct development

no true free-living larval stage, juvenile→ adult, k-selected

Mixed development

internal fertilization, limited parental care

Placozoan cells

gland (mucus, digestive enzymes)

cover cells

fiber cells

cylinder cells

How is Placozoan an animal?

animal cells, moves with purpose

Placozoan: Feeding/ Digestions

No mouth/ gut

extra/intra-cellular digestion (phagocytosis)

Phagocytosis

takes in extracellular fluids + other dissolved fluids → engulfe in membrane

Placozoan; body systems

no muscles

no circulatory structures

no neurons

no excretory system- diffuses waste

no basement layer

Porifera

(phylum) “pore bearer”

Porifera; Calcarea

skeletal spicules of calcium carbonate

~ 685 species

Porifera; Hexactinellida

Glass sponges; 6-rayed silica spicules

deep sea- uses current

~ 690 species

Porifera: Demospongiae

silica spicules and/or organic skeleton (spongin)

~7,400

Porifera: Homoscleromorpha

lack spongin, lack spicules

basement membrane

~85 species

Porifera: bauplan

lacking/ radical symmetry

lack organs= colony of cells

no tissues, no basement layer

no germ layers (no body cavity)

no gut

Porifera; Pinacoderm

outer body wall

Porifera: choanoderm

middle body wall

Porifera: mesonyl

inner body wall

Porifera: Cell types

Pinacocytes; outer skin, pores, protection

Choanoctyes; “caller cell’, do everything

Sclerocytes; “tube cell”, water passes through

Archaneocytes; “Stem”, becomes anything

Porifera: skeleton

in mesonyl

mycicytes- muscle cells

“sneezing’- contractinf

Inorganic spicules

calclium carbonate, silica

Sclerocytes

Organic spicules

collagen fibers, spongin

Ostia

water in

Ostulum

water out

Porifera: Feeding

no mouth/gut

canals~ choanoctes: pumps

Porifera: Coeanocytes

coordinate with other cells

captures particles with collar

Phagocytosis

carnivorous sponges- sharp spicules

Porifera: circulation,gas exchange, excretion

no specialized structure

diffusion only!

What is needed for diffusion to work

high surface area touching water at all times

very thin (1-2 ml)

Porifera: Nervous system

no nuerons

cell-to-cell communication

→ choanocytes beat together- water circulation

Porifera Asexual Reproduction

budding- piece comes off, grows

fragmentation- sponge falls apart, pieces become singular

*regenerative*

Gemmule→ only freshwater! (seed-like)

Porifera: Sexual Reproduction

seperate sexes + herm.

gametes from other cells (interstitial)

broadcast spawning (sperm)

→ Choanoctyles, differentiate between sperm/ egg, move to deliver, carrier cell

Oviparity

yolk in egg, no additional input, not live birth

Ovovivparity

yolk-fed, live-birth, internal ferilization

Viviparity

live birth, placenta- not yolk, direct nutrients

Porifera: Development

different cleavage patterns

cilia covered, short-lived larva

free-living larva: mixed/indirect development

Cnidarians

“Nettles”

~13,400 species

Anthozoa; Anthozoa

“flower animal”

polyps

lack medusae stage

Medusaozoa; Hydrozoa

“snake hair”

alteration of generation

medusae w/ venom

often colonial

Medusozoa: Scyphozoa

→ lions mane, moon jelly

medusa stage dominant

lack venom

Medusozoa: Cubozoa

metamorphosis: polyps→ medusa

square, cube shaped

tentacle from padalia

Myxozoa

intracellular parasites

lack most cnidarian traits

Cnidarians: Bauplan

radical symmetry

oral-aboral body axis

true tissues present

Diploblastic + mesoglea

alteration of generations (diff body, same genes)

Cnidarians: Ectoderm

Epiderms

Cnidarians: Endoderm

Gastrodermis

Cnidarians: polyp

sessile

solitary/ colonial (asexual reproduction)

mouth + tentacle up, disc down

trunk + gastrovascular cavity

Cnidarians: Medusa

motile, pelagic

solitary

mouth+ tentacle down

umbrella up

gastrovascular cavity in canals

Cnidarians

Epidermis: protection

Mesoglea: structure

Gastrodermis: digestion, circulation

Cnidarians Cell Types

Myoepithelial - muscles, skin cells

Muscus gland cell- produce mucus

Digestive gland cells- break down food

Nuerons

Interstitial- stem cells (become things)

Chinocytes- stinging cell

Cnidarians Skeleton

Hydrostatic- flexible

Rigid - perisac of hydrozoan polyps; “Shell”

Cnidarians: Locomotion

circular, longitudinal extension from myoepithelial

elastic fibers

polyps; contraction, swimming, digging

medusae; jet propulsion

Cnidarians: Feeding/ Digestion

All carnivore/ parasitic

Cnidoctyes- stinging cells

→ Nematocyst: organelle inside cnidoctyes- prey moves to mouth

secretory glands of gastrovascular

Phagocytosis

waste sent back through mouth

Cnidarians: alt. feeding

mucus net-suspesion

autotrophic symbionts

→ Zooxanthellae (brown/gold- marine), Zoochlorellae (green-freshwater)

Cnidarians: circulation, gas exchange, excretion

no specialized structures

diffusion

Cnidarians: nervous system/ sensory

neurons form nerve net

no cephalization

naked + nonpolar

Rhopalia

Statolith

pigment spots/cup- “eyes”

Rhopalia

seen easily on young

concentration of different kinds of sensory structures

chemoreceptors- tongue (taste and texture)

Statolith

equilibirum!!