A. The Barnacles (see material page 389 in text) 1. Members of the Class Cirripedia 2. Have motile larval stage that is part of the meroplankton a. larval stage can prevent competition with parents b. can allow for dispersal c. organism can select final place and can go back up in plankton if place is not suitable 3. Larval stage settles out and cement gland on anterior end anchors the creature to the substrate. Animal either forms plates around the body that are attached to the substrate (acorn barnacles) or forms a long stalk with creature at the end surround by plates (gooseneck barnacles) 4. Uses fuzzy thoracic appendages for feeding. Opens tergum (operculum) and either just simply allows water to flow through the appendages or sweeps the appendages through the water. 5. Import design criterion--size of "pore" in filter must not be so large as to allow materials to pass through untrapped or so small as to trap everything. If everything is trapped, then movement of appendages would produce back current that would actually flush materials out of the filter. 6. Barnacles are typically attached to the fixed substrate, but some species use whales, floating debris, etc. as homes. B. Filter feeding in bivalves (see text 293- 295) 1. We will only talk about lamellibranch bivalves. 2. Mantle cavity is coverdy by the mantle. The mantle at the anterior end is developed into two siphons, excurrent and incurrent. The incurrent leads into the incurrent chamber 3. Hanging down into the incurrent chamber are two pair of lamellibranch gills. These are covered by cilia which cause a current of water to pass through the gills and into the excurrent chamber. Food items are caught on the filaments of the gills. 4. Food items are carried to the base of the gills and transported towards the palps where materials are sorted as to whether to be ingested or not. Items not ingested are passed into the excurrent stream 5. To avoid contaiminating the incurrent stream with the excurrent stream, the siphons are somewhat pointed in different directions. In some cases, the siphons are extensible and incurrent can function as a "vacuum" cleaner spout that is moved about the substrate in the vicinity of the clam. 6. In bivalves that are totally attached (eg., oysters=Ostrea), it is important for the animal to know the quality of the incoming fluid. During times of high turbidity, it would be important to shut down rather than to keep filtering and clog up the gills. The animal as structures called osphraedia that can detect the incoming stream. For the oyster which uses glycogen as a storage form of energy, shutting up and becoming anaerobic is no big deal. The are able to convert glycogen to glucose and then to process the glucose via glycolysis (anerobically). They can stay in this state for a fairly long period of time. C. The annelids--Chaetopterus (see picture page 223) 1. Animal lives in u-shaped tube 2. Have highly modified parapodia which are used as fans to produce a current through the burrow. In the vicinity of the mouth there is a mucous bag though which the water must flow. At the end of the bag there is a food cup where trapped particles pass into. The bag is held open by a modified pair of parapodia. D. Annelidlike creatures--Urechis caupo, the innkeeper 1. Member of the Phylum Echiura, a group with ties to the annelids 2. Also live in a u-shaped burrow, which also harbors a number of commensals. 3. Uses peristalic movement of body to pump water through the burrow. 4. Produces a mucous net. Animal moves forward in the burrow to attached edges of net to burrow walls, then moves back as it produces mucous in order form a mucous cone. Water passes through the cone and materials are trapped in the mucous. Animal when net is full, then swallow the net, mucous and trapped food. (see photo and drawing page 249 and 250)