Download ENVI 21 Life in the Ocean

Invertebrates I:
Porifera, Cnidaria,
Tree
of
Life
Figure CO 7
Invertebrates - Background
Kingdom Animalia
I.
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97% of all animal species are invertebrates
Animals without a backbone
All major groups have marine representatives
(some are exclusively marine)
(3-15 million species)
Phylum Porifera (Sponges)
II.
Simplest multicellular animals
Most are marine (~9000 species)
Sessile (attached to substrate)
Diversity of shapes, sizes, colors, habitats
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Found from low tide line to 3.5 miles deep
Shapes:
Tiny cups, broad branches, tall vases, encrusting round masses
III.
Phylum Cnidaria
Big steps from
simple sponges to
evolution of tissues
> 10,000 species
All are aquatic,
mostly marine
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Sea anemones
Corals
Jellies
III. Phylum Cnidaria
Radial symmetry- similar parts
of body are arranged and
repeated around central
axis. Look the same from
all sides and have neither
head or tail, front or back
Oral surface (mouth)
Aboral surface (opposite)
Fig. 7.5
III. Phylum Cnidaria
2 basic forms
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Polyp: anemone, tube with a mouth surrounded
by tentacles, specialized in sedentary (sessile) life
attached to substrate
Medusa: jellyfish, bell-shaped free-floating, swim
by pulsating contractions
III. Phylum Cnidaria-feeding
No true organs
Tube/sac with single opening (mouth)
Mouth opens to gut
Tentacles capture food
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CNIDOCYSTS (stinging cells, NOTE
NAME)
Defense
Prey capture
Contain NEMATOCYSTS =thread
bag (stinging capsule)
Simple nervous system
Trap food using mucus secreted at mouth
and tentacles
Some with symbiotic zooxanthellae,
provides host with nutrients, O2, use
up CO2
III. Phylum Cnidaria
4 Classes of cnidarians
Class Hydrozoa (includes hydras, hydroids,
hydromedusae, chondrophorans, siphonophores,
hydrocorallines)
Feathery, bushy colonies of tiny polyps attach to
pilings, shells, surfaces
Alternate between polyp and medusa form
III. Phylum Cnidaria
Class Scyphozoa-jellyfishes
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All marine species, few hundred
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Medusae large (dominant stage)
E.g. – Cyanea capillata (Lion’s Mane)
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Desmonema glaciale
Bell > 2 m
Tentacles 60+ m
Swim by contracting bell
rhythmically, pulsing contraction,
at mercy of currents
Stings *, sometimes fatal
Aurelia
Cyanea capillata
III. Phylum Cnidaria
Class Anthozoa (most are)
Polyp (more complex than hydrozoan, scyphozoan
Sexes usually separate
Oviparous (egg-bearer) and viviparous (young bearing)
Passive suspension feeders
Solitary forms
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Colonial forms
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Anthopleura xanthogrammica
Sea anemones
Corals
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Stony corals – branching and massive
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- Some build reefs
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Soft corals
Gorgonians
Sea pens
Sea pansies
(Drawings: Brain coral and Gorgonian specimen)
Branching Corals
Doming Corals
Sea Pen
Soft Corals
Sea Pansy
Gorgonians (Sea Whips)
Gorgonians (Sea Fans)
III. Phylum Cnidaria
Class Cubozoa, “scyphozoa cubed”
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Sea wasps, Box jellyfish
square bell-cuboidal swimming bell
4 tentacles or bunches
Highly toxic
IV. Phylum Ctenophora (comb-bearing)
Exclusively Marine (100 species)
Aka comb jellies
Resemble Cnidarians
Most primitive
Biradial symmetry (radial + bilateral symmetry)
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8 rows of ciliary combs (ctenes)
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Equally spaced on body surface
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Each row is a ridge, paddle of fused cilia
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Beat aboral to oral, propels mouth forward
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Organ system: Digestive system-mouth to pharynx to stomach
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Predatory and Carnivorous
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Lack nematocysts
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Capture prey with sticky colloblasts
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May occur in swarms
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Heavy predators
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(consume lots of fish larvae)
Pleurobrachia
Beroe