1. Marine Invertebrates

2. Who are the Invertebrates?
Any animal lacking a backbone
Lamarck (1809)
98% of all animal species (Fig. 7.1)
Diversity rules in all aspects of their life
feeding (filter, predator, parasitic…)
morphology (stars, threads, torpedoes…)
reproduction(sexual, asexual)
habitats (benthic, pelagic, intertidal, open ocean)

3. Why study Invertebrates?
Ecological importance
Economic importance
Medical importance
Learning Strategy:
From simplest to most complex in terms of body organization.
Major taxa only
Unique (defining) features of each taxa

4. Phylum Porifera (The sponges)
Latin “Pore-bearers”
Body plan simple:
Multicellular, but without tissues
encrusting, globular, vaselike…

5. Sessile lifestyle
feeding - forced water flow through flagellated channels
two cell layers
choanocytes = flagellated cells
pinacocytes = outer covering
spicules of SiO3 or CaCO3 give support
ostia = incurrent pores
osculum = excurrent pore

6. Phylum Cnidaria Greek “stinging thread” Body plan (Fig. 7.3)
tissue level of construction (2 layers with mesoglea between)
2 alternate body plans:
polyp = sessile (anemone, corals)
medusa = free-floating (jellyfish)
Many species possess both body plans in their life cycle (Fig. 7.4)
Many species are colonial (polyp or medusa) (Fig. 7.5)

7. Regardless of body plan type, all have:
radial symmetry
gastrovascular cavity with one opening
tentacles surrounding mouth
batteries of stinging cells (cnidocytes)
each cnidocyte contains a nematocyst
barbed
sticky
toxic
nematocysts discarged explosively for defense or prey capture

8. Class Hydrozoa Greek “water animals” Ex. Physalia
medusa with gas (N) filled pneumatophore
colonial organism with polyp members dangling beneath medusa
reproduction
digestion
offense/defense

10. Class Anthozoa Greek “flower animals” Ex. Hard corals
polypoid body plan
colonial organization
secrete hard “cup” of CaCO3
layers of calcium carbonate build up to form reefs
endosymbiotic algae provide nutrients
Healthy reefs - clear, clean, shallow water

13. Class Scyphozoa Greek “cup animals” Ex. Moon jelly Aurelia
almost exclusively medusa form
solitary
predatory

15. Phylum Ctenophora Greek “comb bearer” (Fig. 7.6)
Very similar to Cnidarians
no nematocysts
rows of fused cilia called combs or “ctenes” for locomotion

16. Marine Worms
Since they belong to 13 different phyla, many differences exist between these organisms.
Shared characteristics:
worm-like (vermiform)
bilateral symmetry with cephalization
efficient swimming, burrowing, tube-dwelling, and parasitic lifestyles

17. Phylum Annelida Latin: annulus or “ring”
Most common group of marine worms
Body - segments (metamerism) with repeating body parts.
Possess tissues / organs / organ systems (nervous, digestive, reproductive, excretory) and extensive musculature.
Fig. 7.7a

18. Burrowing lifestyle: ex. Arenicola
lives in a L-shaped burrow in intertidal mud and sand
ingest sand/food at bottom of burrow and defecate undigestible parts at surface

20. Tube-dwelling lifestyle Ex. Feather dusters
secrete parchment-like tubes to inhabit.
extend tentacles to collect particles (suspension feeders).
Retract tentacles into tube for protection

22. Free-living lifestyle Ex. Fireworms
swim (although not particularly speedy) often using modified flaps of skin called parapodia.
Usually deposit feeders
Predatory species often use
jaws (annelids) (Fig. 7.7a)
special harpoon devices (nemerteans) (Fig. 7.7e)

23. ex. Nematodes, tapeworms and flukes
Parasitic lifestyle
ex. Nematodes, tapeworms and flukes
complex life cycles often including multiple hosts
definitive hosts usually vertebrate (in muscles, digestive tract, nasal and bronchial areas)

25. Phylum Mollusca Latin “soft”
Second largest animal phylum (after arthropods)
Extreme variation in size and shape

26. Shared characteristics: (Fig. 7.9)
visceral mass containing organ systems
heart in pericardial cavity
ganglia and nerve cords
usually separate sexes (dioecious)
Mantle = secretes shell
foot = modified for movement and food acquisition
radula = tongue-like structure with teeth for scraping food

27. Radula movie

28. Class Gastropoda (Fig. 7.11)
Greek “stomach foot”
ex. Snails, conchs, limpets, nudibranchs
single, coiled shell when present
may graze using radula to scrape diatoms and algae, set mucus nets, or be predaceous.
Trochophore and veliger larvae swim to allow dispersal (adults heavy, slow)

31. Class Bivalvia (Fig. 7.12) Latin “two shells”
ex. Clams, oysters, scallops
no radula, collect debris on leaf-like gills = ctenidia (in mantle cavity) and stuff into mouth.
bacteria and viruses (from sewage), and pollutants, concentrated in visceral mass
significant health risk to humans if poorly cooked prior to consumption.

33. Class Cephalopoda (Fig. 7.13)
Greek “head foot”
ex. Squid, octopus, nautilus
shell variable (reduced, absent, present)
most highly cephalized of all marine invertebrates
eyes highly developed
rapid swimmers (some) by jet propulsion
multiple muscular arms with suckers
all predaceous carnivores
able to learn and problem-solve

34. Squid swimming

35. Class Polyphacophora (Fig. 7.14)
Greek “many plate-bearer”
ex. chitons
shells of 8 overlapping plates
grazers using radula