Porifera, Cnidarians, and Ctenophora (Invertebrates 1)

metazoans

multicellular animals

synapomorphies of metazoans

-extracellular matrix w/ collagen (connective tissue)

signaling molecules

-blastula stage of development

Porifera

-sponges, the first visibly multicellular “animal”

-few cell types, no tissues, organs, no gut cavity

ostia

pores that allow water to come into the sponge

pinacoderm

outermost layer of cells; similar to epidermis

mesohyl

gelatinous matrix, acts as an endoskeleton in sponges

canal system

openings used for feeding an reproduction

spongocoel

large central cavity

osculum

large aperture were water is expelled

spicules

supporting and/or defensive skeletal structure

the three kinds of spicules

-spongin: collagen

-calcium carbonate: hard, calcium-rich

-silica: look like glass, often defensive

the three main sponge cell types

-choanocytes

-pinacocytes

-archaeocytes

choanocytes

-acts like a fan that creates a vortex to pull water through the sponge using flagella

-work w/ collenocytes to catch prey

-help to release gametes and absorb nutrients

pinacocytes

-”skin cells” of the sponge

-line exterior of sponge body wall

-thin, leathery, tightly packed together

archaeocytes

-totipotent: can change into all other cell types of sponges

-similar to stem cells

-ingest & digest food caught by the choanocytes and transport nutrients to other cells

-can develop into gametes

sponge reproduction

-asexual: external buds or gemmules

-sexual: gametes unite to form zygote, develops in parechymul or amphiblastula larva

-able to form into two separate sponges when cut in hald thanks to archeocytes

the three main sponge shapes

-asconoid: simplest sponges, usually tube shaped

-syconoid: more complex w/ branching channels that elad to the atrium

-leuconoid: most complex w/ branched canal system that leads to digestive chambers

classes in phylum porifera

-Homoscleromorpha

-Calcispongiae

-Demospongiae

-Hexactinellida

class Homoscleromorpha

a class of sponges that:

-lack spicules or have poorly developed spicules

-gelatinous/slimy

-live in deeper ocean

originally group w/ Demospongiae

class Calcispongiae

a class of sponges that:

-are usually small

-tubular or vase shaped

-can be any of the three shapes

-calcium-rich in spicules

-marine

class Demospongiae

a class of sponges that:

-95% of all sponges

-marine or freshwater (only freshwater sponge class)

-all leuconoid

-skeleton of silica, spongin, or both

class Hexactinellida

a class of sponges that are:

-”glass sponges”

-deep sea

-six-rayed highly siliceous spicules fused together

-very prickly, used for protection

-only leuconoid

bioindicator

an organism that can be used as an indicator for the health of an ecosystem (i.e. pollution, pH, etc.)

bioaccumulators

can remove pollutants from the water

Phylum Placozoa

-single species

-thought to be sponges until recently

-filter feed w/ flagellum

-don’t have main 3 cell types

Phylum Cnidarians

-coral, jellyfish, anemone, and hydroids (hydras)

-all have cnidocyts (stinging cells that contain nematocysts)

Cnidarian body plans

-Two main body types:

• Polyps: tentacles facing upwards w/ stinging cells over entire body

• Medusa: tentacles facing downwards w/ stinging cells only on tentacles

-blind guts (one opening for both feeding and excretion)

-radial symmetry

-both intra and extracellular digestion

-diploblastic w/ a “skin”

-no true muscle cells, only epitheliomuscular cells, controlled by nerve net of neurons

Class Anthozoa

a class of cnidarians that:

-are the largest class

-include sea anemones and stony corals

• hard corals (Subclass Hexacorallia)

• soft corals (Subclass Octatoria)

-form coral reefs

Class Hydrozoa

a class of cnidarians that:

-includes hydra and siphonophores (man o’ war)

• hydra are only freshwater, no medusa

• man o’ war are colonial w/ individual zooids

Class Scyphozoa

a class of cnidarians that:

-include “true jellies”

-have arms around the mouth

-tentacles can be long and short

Class Cubozoa

a class of cnidarians that include:

-box jellyfish

-have pedaliums, which are the base of the tentacle

-have eyes

have velarium, which is the sub-umbrella

Class Staurozoa

a class of cnidarians that:

-look like a star

Subphylum Myxozoa

a subphylum of cnidarians that:

-are now considered cnidarians

Phylum Ctenophora

-diploblastic

-no cnidocytes (stinging cells)

-8 comb rows, constantly pump water into body

-comb jellies