Marb 435 1st Edition Lecture 15 Current Lecture Phylum 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 m max 3 mm Free living species are often cultured as a food source in fish farming Morphology 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 pellets Feeding 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 prey Locomotion These 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 attachment Reproduction 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 stage Phylum 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 species Feeding 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 ingestion Reproduction 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 stage Lophophorates Common Features Lophophore Sessile Suspension feeders Shell tube or exoskeleton with a single aperture U shaped gut Radial cleavage Lophophore Crown of ciliated tentacles forming a funnel upstream 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 mouth Phylum phoronida Only 14 species in two genera Exclusively marine Secrete chitinous tube Externally bilaterally symmetrical but internally asymmetrical with left side dominance Phylum 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 freshwater Coloniality Often involves polymorphism of zooids autozooids for feeding heterozooids for other functions Defense e g auicularia Attachment Reproduction Cristatella mucedo Wandering colony of freshwater bryozoans Form statoblasts dormant stages with chitinous valves Statoblasts withstand passage through digestive tract of ducks Dispersal through water fowl Bryostatins 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 difficult Phylum 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 lophophore