Marb 435 1st Edition Lecture 15Current LecturePhylum Rotifera A.k.a. “wheel animals” Approximately 1850 species, of which 95% live in freshwater and 5% in seawater Many can enter criptobiosis Some are free-swimming, others permanently attached; some parasites Usually < 500 μm (max. ~ 3 mm) Free-living species are often cultured as a food source in fish farmingMorphology and anatomy Pseudocoelomates Eutelic (i.e. cell number is fixed; growth by increasing cell size) Syncytial epidermis with intracellular cuticle that never molds; may form Lorica Lacking blood and respiratory systems Some produce tubes that may incorporate debris, sand grains or fecal pelletsFeeding Biology Mostly suspension feeders on phytoplankton, bacteria and small zooplankton Unique structures:  Mastax is a muscular modification of the pharynx Trophi are used to grind food, suck food in through the mouth or protrude from the mouth and pierce preyLocomotionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Swimming with coronal Some have spines in addition that are used in oar-like motion Temporary or permanent attachment with toes at the posterior end looping: Interplay between circular and longitudinal musculature and posterior and anterior attachmentReproduction and Development Often exclusively by parthenogenesis (no other forms of asexual reproduction known) If males are present in a population, they are often small and short-lived (dwarf males) All cell divisions occur before hatching; postembryonic growth exclusively by increasing cell size or spacing (eutely) No larval stagePhylum Chaetognatha A.k.a. arrow worms Free-living, marine carnivores Most species are planktonic, but some attach themselves using adhesive papillae Mostly small (largest individuals 15 cm) and transparent Approximately 150 speciesFeeding biology Feed mostly on copepods and fish larvae, sometimes as big as themselves Hang motionless in the water until prey approaches Dart forward and grasp prey with spines At least some species produce paralytic neurotoxins (tetrodotoxin) to subdue prey before ingestionReproduction and development All chaetognaths are simultaneous hermaphrodites Produce spermatophores in seminal vessicles that are transferred by attaching them to the outside of a recipient’s body Sperm migrate along the body to the female reproductive tract Internal fertilization No larval stageLophophoratesCommon Features Lophophore Sessile Suspension feeders Shell, tube or exoskeleton with a single aperture U-shaped gut Radial cleavage(?)LophophoreCrown of ciliated tentacles forming a funnelupstream food collecting system:• Cilia on lateral sides of tentacles create water current into the funnel• Cilia on upstream (= inside) side of funnel transport food particles to the mouthPhylum phoronida Only 14 species in two genera Exclusively marine Secrete chitinous tube  Externally bilaterally symmetrical, but internally asymmetrical with left side dominancePhylum Bryozoa a.k.a. Moss animals About 5000 living species Most species living attached to firm substrates Benthic and colonial (except 1 species) Colonies consists of many individual zooids Most are marine, but some are freshwaterColoniality Often involves polymorphism of zooids autozooids for feeding heterozooids for other functions• Defense (e.g. auicularia)• Attachment• ReproductionCristatella mucedo Wandering colony of freshwater bryozoans Form statoblasts (dormant stages) with chitinous valves Statoblasts withstand passage through digestive tract of ducks Dispersal through water fowlBryostatins Anti-cancer agents against leukemia, lung and prostrate cancer Discovered in the bryozoan Bugula neritina Probably produced by symbiotic bacteria as a predator defense Concentrations are too low to be efficiently extracted (1 tonne of bryozoans yields 1 g of bryostatin) Synthesis has been difficultPhylum Brachiopoda a.k.a lamp shells Bivalved calcareous shell: dorsal and ventral valve Exclusively marine Intertidal to deep sea About 350 extant species but about 12,000 described fossil species Were extremely common in the paleozoic but were decimated in the permio/triassic Mass Extinction (250 mya) Large