Chapter+6

Return to Marine Biololgy Chapter 6 Invertebrates

Sponges / Poriferans http://www.ucmp.berkeley.edu/porifera/porifera.html
 * They have tiny pores instead of mouths
 * Most of their cells line a series of connected chambers and channels
 * They are composed of collar cells, pore cells, and wandering cells which can easily change type
 * Water is drawn into the pores and out the top of the sponge by flagella
 * Collar cells filter food from the water as it passes by.
 * Cells function independently and perform a variety of functions.
 * Spicules and spongin are use for support

Cnidarians/Anemones, Jellyfish, Corals http://www.ucmp.berkeley.edu/cnidaria/cnidaria.html
 * Grouped together because many of the species have a particular type of sting-cell
 * Most have a polyp or sack like stage and a medusa or bell shaped stage.
 * They have not head, no skeleton, and no special organs for respiration or excretion
 * They have:
 * Nematocysts – stinging-cells that eject barbed threads tipped with poison
 * Radial symmetry, where similar body parts encircle a central axis
 * Mouths surround by tenticles
 * Mouth sides (oral surfaces) and sides away from the mouth (aboral surfaces)
 * Blind gut cavities
 * Body walls with two layers of cells
 * Nerve-nets – interconnected neurons lacking a brain http://faculty.washington.edu/chudler/invert.html

Three Common Groups of Cnidarians: Hydrozoans http://www.ucmp.berkeley.edu/cnidaria/hydrozoa.html Scyphozoans http://www.ucmp.berkeley.edu/cnidaria/scyphozoa.html Anthozoans http://www.ucmp.berkeley.edu/cnidaria/anthozoa.html
 * Are the most diverse group
 * Some form feathery or bushy colonies
 * Some form drifting colonies
 * Some have specialized floats
 * Unlike true jellyfish they are composed of colonies of individuals, all specialized for various functions
 * Examples: hydra, fire corals, and the "Portuguese man-o'war."
 * The larger, true, jellyfish
 * The medusa is the dominant stage in most
 * Swim with rhythmic contractions
 * Most lack a medusa stage
 * They exist as solitary or colonial polyps (corals)
 * Some have large muscular polyps (anemones)
 * Some have calcium carbonate skeletons (corals)
 * Some have branching protein skeletons (Sea fans and black corals)
 * Some form fleshy colonies (Soft corals, sea pens, and sea pansies)

Flat Worms / Platyhelminthes Trematoda, or flukes, are all parasitic (live in lungs and liver tissue) The Cestoda, or tapeworms, are intestinal parasites in vertebrates http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html http://www.biocrawler.com/encyclopedia/Flatworm__
 * Simplest animals with three cell layers
 * bilaterally symmetrical – could be cut into two similar halves
 * Has a gut, but no anus (Food and wastes move through the same opening)
 * Gut may be branched, so it is close to more cells
 * Respires by diffusion, so a flat shape keeps a surface close to more cells
 * Brain is just a small group of nerve cells in the head

Ribbon Worms / Nemerteans http://www.ucmp.berkeley.edu/nemertini/nemertini.html http://www.biocrawler.com/encyclopedia/Nemertea
 * Gut includes a mouth and anus
 * Blood transports nutrients and oxygen to tissues
 * Proboscis – long fleshy tube to entangle prey
 * Longest animal on earth

Roundworms / Nematodes Live in sediments or are parasites They have: http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html http://www.biocrawler.com/encyclopedia/Roundworms
 * Cylindrical bodies with points on both ends
 * A mouth and anus
 * A gut that lies in a fluid filled body that transports nutrients
 * A hydrostatic skeleton made by layer of muscle that pushes and squeezes the fluid filled body aiding movement

Segmented Worms / Annelids They have: Some have extensions of the body wall that absorb oxygen – gills Some have specializations to suck blood http://www.ucmp.berkeley.edu/annelida/annelida.html http://www.biocrawler.com/encyclopedia/Annelid
 * A body consisting of a series of similar compartments
 * A guts that lies in a cavity called a coelom that passes all segments
 * A fluid filled coelom that a long with muscles in the body wall form a hydrostatic skeleton
 * A closed circulatory system with contractions in vessels moving blood

Lophophorates Three groups of marine invertebrates
 * Bilateral filter feeders with a U-shaped gut
 * They have a unique feed structure called a lophophore.
 * Lophophore are a circular or coiled arrangement of ciliated tentacles.

Bryozoans – moss animals http://www.sms.si.edu/IRLSpec/IntroBryozoa.htm http://www.ucmp.berkeley.edu/bryozoa/bryozoamm.html http://www.tolweb.org/Bryozoa http://www.ucmp.berkeley.edu/bryozoa/bryozoa.html

Phoronids – worm-like and build tubes partially made of sand http://www.ucmp.berkeley.edu/brachiopoda/phoronida.html http://www.solaster-mb.org/mb/phoronida.htm

Brachiopods – have a top and bottom shell, but are very different from clams Many are found in the fossil record. http://en.wikipedia.org/wiki/Brachiopod http://www.ucmp.berkeley.edu/brachiopoda/brachiopoda.html

Mollusks / Snails, sea slugs, clams, octopuses, and chitons Features common to some species:
 * Shell secreted by a thin tissue layer
 * Muscular ventral foot
 * Head with eyes
 * Radula – a rasping tongue
 * Gills
 * Salivary and digestive glands
 * Both closed and open circulatory system

Gastropods Snails, nudibranchs and sea hares http://en.wikipedia.org/wiki/Nudibranch

Bivalves http://en.wikipedia.org/wiki/Bivalves http://www.solaster-mb.org/mb/bivalvia.htm

Cephalopods http://www.tolweb.org/Cephalopoda http://en.wikipedia.org/wiki/Cephalopod____

=Crustaceans= General characteristics: Special share characteristics of some:
 * Segmented bodies
 * Jointed legs
 * Chitinous exoskeleton
 * Two pairs of antenna
 * Mandibles for chewing
 * A pair of appendages on each body segment
 * Teardrop-shaped larvae
 * Molting
 * Compound eyes
 * Small simple brains

Barnacles/ Class Cirripedia
 * Begin as free-swimming larvae
 * Cements its back to a suitable surface
 * Catches or filters food with its feet
 * Forms a calcium carbonate shell
 * Hermaphrodite

Copepods
 * Abundant in plankton and a major food for plankton feeders
 * Filter or capture food with mouthparts
 * Swim with antenna

Decapods and Krill__ / Malacostraca Includes lobsters, crab, and shrimp Characteristics: The large nets used to catch shrimp often kill many other kinds of animals
 * Ten legs
 * Claws
 * Carapace that encloses the gills