Marine Mammals without a Backbone Marine Biology: Chapter 7
Jan 01, 2016
Lets Get Started…
• Kingdom Animalia
• Organisms of this kingdom must hunt/find their own food
• Two major groups;– Vertebrates: have a backbone– Invertebrates: lacking any backbone
• At least 97% of all species of animals are invertebrates
Suspension vs. Deposit
• Suspension feeders- animals that eat food particles suspended in the water– Filter feeders
• Deposit feeders- animals that eat detritus that settles on the bottom– Detritus- dead “stuff” which sinks to the
bottom of the sea-floor
Sponges
• Sponges do not form true tissues and organs
• Among the structurally simplest organisms
• Sponges are sessile
• Come in all shapes, sizes, and colors, but all have a relatively simple body plan
• Phylum Porifera; “pore bearers” – Contain numerous tiny pores, or ostia
Sponge Anatomy
• Pinacocytes- flat cellson the outer surface• Porocytes/pore cells- allows water to enter• Choanocytes/collar cells- uses a flagella to
create a current and trap food particles• Osculum- water exits from this point• Spicules- support structures
(siliceous/calcareous) • Spongin- skeleton of tough elastic fibers• Amebocytes- secrete spongin and spicules
The Awkward Part..
• Asexual reproduction– Branches and buds of the sponge break off
and grow into separate sponges
• Sexual reproduction– Produce gametes, large nutrient-rich eggs
and smaller sperm cells that have flagellum– Broadcast spawning- sperm are released into
the water and enter a sponge containing eggs
Growing Up!
• Early stages of development occur within the sponge
• Larva is released into the water
• Carried by currents until it settles on the bottom and develops into a cute tiny baby sponge
Just a little more…
• 6,000 known species of sponge• Mostly inhabit shallow tropical waters• Branching, tubular, round, volcano-like• Encrusting- thin growths on rocks/dead coral• Glass Sponges- anchored in deep-water,
have lace-like structures• Boring Sponges- bore channels in CaCO3• Coralline Sponges
Body Parts
• Tentacles- finger-like extensions to collect food• Gut- food is digested, connected to the mouth• Nematocysts- stinging structures • Polyp- sessile stage • Medusa- upside down polyp adapted for swimming• Planula- Larva, consisting of 2 layers of cells• Epidermis- 1 of the two layers, the outer part• Gastrodermis- Internal layer, lines the gut• Mesoglea- gelatinous middle layer
Hydrozoans
• Hydrozoans– Wide range of forms– Many consist of colonies of tiny polyps– Do not always consist of a polyp stage, and
some lack a medusa stage
• Siphonophores • Drifting colonies of polyps• Portuguese Man-O-War
Scyphozoans
• Scyphozoa– Larger jellyfishes, with larger medusae– Planktonic- easily carried by currents– Have a bell-shaped ‘head’
• Swim with contractions of the bell
– Some of the most dangerous marine creatures
Anthozoans
• Anthozoa– Solitary/colonial polyps that lack a medusa stage– More complex than hydrozoans or scyphozoans
• Septa- within the gut, used for support and help with digestion
– Sea anemones, corals
Corals
• Calcium carbonate skeletons• Tropical waters• Gorgonians- Secrete a tough branching
skeleton (Sea fans)• Precious Corals- gorgonians with red/pink
spicules as well• Black Corals- Secrete a hard black protein
skeleton – Black and precious carved into jewelry
Feeding and Digestion
• Almost all are carnviores
• Capture and digest food larger than that of filter feeders
• Use their nematocysts primarily to capture prey
Behavior
• No brain or true nerves
• They do have specialized nerve cells– These cells interconnect to form a nerve net
that transmits impulses in all direction
• Statocysts- Small calcareous bodies in fluid-filled chambers surrounded by sensitive hairs- give them a sense of balance
Flatworms
• Platyhelminthes– Have a central nervous system where
information is stored processed– Have a SIMPLE brain- just an aggregation of
nerve cells in the head– More complex tissues than that of cnidarians– Turbellarians- free living carnivores– Flukes/trematodes(largest group)- parasites– Tapeworms/cestodes- parasites, looooong body
Ribbon Worms
• Nemertea
• More complex degree of organization
• Have a circulatory system
• Proboscis- a long fleshy tube used to entangle prey
Nematodes
• Also known as roundworms
• Hardly ever seen, but are often found in sediments
• Many are parasitic
• Small with cylindrical bodies which are pointed at both ends
• Feed on bacteria and organic material
• Sushi- OH NO!!!
Segmented Worms
• Annelids– Earth and marine worms
• Consists of segments
• The gut goes through all the segments and lies in the cavity known as a coelom
• Polychaetes– Closed circulatory system– Have gills