BIOL Chapter 28

Sponge body plan and cell types

spicules and spongin

spicules - made of silica or calcium carbonate

spongin- protein fibers (collagen like)

made by amoebacytes in mesohyl

asexual reproduction of sponges

fragmentation or budding

s*xual reproduction of sponges

hermaphroditic (M or F at diff times)

• no gonads: gametes form in mesohyl

• flagellated larvae disperse, then settle

phylum cnidaria

jellyfish, hydra, anemones, corals

• Radial symmetry, diploblastic

• Aquatic: 2 body forms

  • sessile polyp- not moving

  • drifting/free swimming medusa

  • No cephalization

  • Oral and aboral side

cnidaria

sac like body with gastrovascular cavity

1 opening as mouth/anus to digestive sac

• mesoglea

  • nervous system

mesoglea

non cellular layer functions as hydrostatic skeleton (flexible, supported by fluid pressure)

nervous system

simple, coordinated by non-centralized nerve net

nematocysts and cnidaria

aquatic sit and wait carnivores, ex: sea anemone

stinging tentacles around central mouth

cast prey with cnidocytes

nematocyst organelle inside cnidocyte

ctenophora

radially symmetric and dipoblastic

• transparent, medusa-like body

• moves with cilia, fused into 8 comb-like plates

marine carnivores

• only 2 tentacles or none

  • eject a sticky thread to capture prey

  • some engulf prey

porifera vs. cnidaria

lophotrochozoa

lopopohore- for feeding, others pass through a trochopore larval stage (either/or) but a few have neither

• platyhelminthes

• syndermata

• annelida

• mollusca

• ectoprocta

• brachiopoda

• gastrotricha

• cycliphora

• nemertea

ectoprocta

crown of ciliated tentacles (lophophore) around mouth used for feeding

platyhelminthes

flatworms

live in marine, freshwater, and damp terrestrial habitats

many are parasites ex: flukes (have prominent gonads and an oral sucker on the other end) and tapeworms

use mucus to move

flat shape increases surface area to absorb food

gas exchange and elimination of nitrogenous waste can occur by diffusion across body surface

are acoelomates

yes cephalization

gastrovascular cavity w 1 opening (highly branches to digest and distribute nutrients)

O2/CO2 exchange is at cell level

Have: digestive, nervous, excretory, and reproduction system

flatworm nervous system

centralized collection of nerves, ganglia, ventral nerve cords, eyespots

excretory system of flatworms

protonephridia with flame cells to remove excess **

tapeworms

parasitic, mostly in vertebrate intestines

humans get them by eating undercooked infected beef, pork, fish

do not have mouth or gastrovascular cavity, absorbs nutrients from host intestine

has a scolex, a head with no eyes or mouth with suckers and hooks

segments called proglotids

proglottids

repeated reproductive segments filled up fertilized eggs

syndermata (rotifers)

free-living, aquatic

microscopic, cylindrical body

crown of cilia - draws vortex of water into the mouth

jaws- grind up food (microorganisms)

pseudocoelom

alimentary canal present (digestive tube with 2 openings, mouth and anus)

parthenogenesis- asexual, females produce more females from unfertilized eggs

invertebrates

are animals that lack a backbone

• They account for more than 97% of known animal species

• Are morphologically diverse and occupy almost every habitat on Earth

• More than 35 phyla identified

phylum: porifera

the Sponges

• Aquatic, mostly marine

• Motility : Sessile as adults

  • No Nervous, digestive, respiratory, circulatory, or reproductive system

  • Filter feeders

  • No true tissue or cephalization