Transcript Sponges, Cnidarians, Worms

Animals
sans Backbone
How are we related??
Introduction
• Most (97%) of the amazing life which is located
within the oceans, or anywhere else, doesn’t have a
backbone!
• In every class of invertebrate we can find a marine
example…convenient, eh?
Summary of Invertebrates
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Sponges-sponge
Cnidarians- “jellyfish”
Comb Jellies- comb jellies
Symmetrical Worms-flat, round, segmented worms
Molluscs-snails, clams, oysters, scallops, octopuses
Arthropods-copepods, shrimp, and lobster
Echinoderms- seastars, brittlestars
Chordates-seasquirts
Sponges
• Sponges are really nothing but a loose aggregation
of specialized cells.
• Of the 6,000 known spp. nearly all are marine.
• Amazingly enough, these cells don’t actually form
organs, but do serve similar functions, keeping the
animal(s) alive.
James Fatherree
Porifera-Sponges (the pore bearers)
Spicules are like calcium carbonate or silica re-bar for sponges,
providing support for a larger congregation.
Sponges
• Do they “sits and thinks, or
do they just sits??”
• Sponges are sessile and
remain permanently
attached to the substrate
they alight upon.
Still, if you carve ‘em up, they come back for more!!
It’s more amazing than that. If you mix groups of sponges together,
they will usually reorganize into their original groups.
Suspension feeding: natural water purification
Reproduction: Asexual vs. sexual
Damage to a sponge can actually promote asexual reproduction, as
“parts” can land elsewhere and form new sponges.
Sexual reproduction
• Many sponges are
hermaphrodites, containing
male and female reproductive
capabilities, yet do not selffertilize.
•Tube sponges, such as this
Verongia archeri which is
common in Caribbean waters
use broadcast spawning to
disperse sperm and eggs in
a flurry of activity that is
often coordinated with lunar
cycles.
General Sponge Types
Sponges fall into several basic categories, mostly depending on
shape:
branching
tubular
Hawaiian encrusting sponge
round
encrusting
Harvested sponges
glass
boring (destructive)
Sclerosponge (CaCO3)
Ceratoporella nicholsoni
Cnidarians
Sea anemones, jellyfishes, coral, etc.
Cnidarians
• Finally, we see a pie that
can be sliced!
• Cnidarians actually exhibit
radial symmetry
in which similar body parts
can be grouped around a
central axis.
• Here we also observe a
large jump on the
evolutionary scale: tissues
that perform specific
functions.
General Cnidarian Structure
and Function
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Centrally located mouth
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Oral surface (mouth)
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Aboral surface (opposite end)
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Tentacles
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Gut
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Nematocysts (cnidae)!
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Polyp and Medusa: reproductive
stages
Macrorhynchia phillipina
Beautiful, but deadly! This colonia
hydrozoan still contains cnidae.
Discharged nematocysts,
stingingcells used for defense
and prey capture, have been
the plague of more than fish.
Stings from certain jellyfish
have resulted in death in a
matter of hours, especially
for infants.
Carukia barnesi: the badest of the bad!
Irukandji syndrome:
A sting from this little guy can cause the following:
“It begins with a mild sting, followed by severe lower back pain,
muscle cramps in arms, legs, stomach and chest. It causes sweating,
anxiety, nausea, vomiting, headaches and palpitations, and has also
been known to cause cardiac failure.”
Cnidarians
1. Polyp: a sac-like attached
stage with a mouth and
tentacles (mostly sessile)
2. Medusa: a mobile bell-like
upside down polyp
(jellyfish).
Cnidarians
Types of Cnidaria
Cnidaria come in all shapes and sizes.
•Hydrozoans- feathey hydroids
•Siphonophores- man-o-war
Sea fan
•Scyphozoans- large jellyfish
•Anthozoan-sea anemones and coral
•Most of the animals found within Cnidaria
are all carnivores.
multiple comb jellies
Comb jellies: Ctenophora
Similar to cnidarians in most
respects.
Nearly 100 spp.
Contain cilliary combs which
assist in prey capture and mobility.
Marine Worms, etc.
• Marine worms, and organisms
hereafter, kick it up a notch
exhibiting bilateral symmetry
(just like humans).
• Instead of addressing front and
back, we’ll discuss anterior,
posterior, dorsal and ventral.
• We’ll also pick up a CNS!
• Bilateral symmetry, and all
that goes with it, results in
enhanced motion and
sophisticated behaviors.
Flatworms: Platyhelminthes
•These simple organisms
contain organs and
systems.
•Nearly 20,000 spp. exist
•The most common are
turbellarians, like this
Pseudoiceros gratus from
the Great Barrier Reef (lower
right.)
•About 6,000 spp. are parasitic, ex.
flukes (trematodes) and
tapeworms (cestodes)
(Steve Irwin would be proud
‘cause “She’s a beauty!”)
Ribbon worms look like tapeworms.
However, they exhibit a complete
digestive tract and a circulatory system.
~900 spp. exist
Nematode
• Roundworm numbers are staggering in the marine
world.
• Many animals have them.
• Some even find there way into fish (which we
ingest when we eat sashimi).
Segmented Worms
• 20,000 spp.
• Known as Annelids
• First example of segmentation.
• Allows for flexability and excellent burrowing
ability.
Polycheates-many bristles (setae)
~10,000 spp.
Exhibit parapodia
Evolution of gills.
Fireworm
Hermodice carunculata
Sandworm Nereis
This feather-duster worm, Sabella melanostigma, is a perfect example
of beauty, form and function.
Next time…
• Gastropods, Molluscs, and Arthropods