Phylum Bryozoa moss animals Bryozoa Characteristics Approximately 4000 pecies of Bryozoans All are aquatic marine or freshwater Body Plan lophoph ore mouth anus esophagus stomach Bryozoa Characteristics Gas Exchange lophophore Circulatory System no organs coelomic fluid Excretion no organs simple diffusion Nervous system nerve ring surrounding pharynx and nerves in tentacles no sensory organs Bryozoa Characteristics Skeletal system most have a cuticle composed of chitin or calcium carbonate zoecium zoecium Bryozoa Characteristics Digestive System lophophore a contractile ring of ciliated tentacles surrounding the mouth complete digestive system U shaped with anus outside lophophore ectoproct lophophore mouth anus Bryozoa Characteristics Reproduction most are monoecious most species brood their eggs externally or within special cavities in their bodies freshwater species are capable of asexual reproduction using statoblasts similar to gemmules statoblasts Bryozoa Characteristics Colonial bryozoans are sessile and live in colonies zoarium colonies can be encrusting thin sheets or stoloniferous plant like encrusting bryozoan stoloniferous bryozoan Bryozoa Characteristics stoloniferous Bryozoan Hydrozoan Superficially stoloniferous Bryozoans resemble colonial Hydrozoans Major differences include the structure of the digestive system the zoecium the number of tissue layers Bryozoa Characteristics Colonial all zooids within a colony zoarium are connected by pores in each individuals zoecium lophophore operculum muscle pore retractor muscle Bryozoa Characteristics Colonial some Bryozoans are polymorphic and contain defensive zooids called avicularia Used in defense and anti fouling th es pseudocoelomates acoelomate at a ho rd at C oz oa ry B a rm de hi no Ec ro po da A rth a a ol lu sc M A nn el id da ot ife ra R N em at o Pl at yh el m in deuterostomes eucoelomates Traditionally Bryozoans were considered to be primitive deuterostomes based on aspects of their development deuterostomes pseudocoelomates acoelomate C ho rd at a rm de hi no Ec ro po da rth A B M r yo ol zo lu a sc a a nn el id A ra ot ife R N em at od a Pl at yh el m at a in th es protostomes eucoelomates More recently they have been placed with the protostomes based on molecular sequence data Phylum Echinodermata spiny skinned animals Echinodermata Characteristics Approximately 6000 species of Echinoderms All are marine and are benthic as adults pseudocoelomates acoelomate em at o R eucoelomates Ch o rd at a at th es a el m in da ot ife r An a ne lid a M ol lu sc a Ar th ro po da Ec hi no de rm N Pl at yh deuterostomes Deuterostome Mouth Formation Blastopore becomes the anus and the mouth forms secondarily Future mouth blastopore archenteron primitive gut anus Deuterostome Radial Cleavage 2 cells 4 cells 8 cells Blastomeres divide in a symmetrical fashion producing layers of cells directly on top of one another Deuterostome Regulative Development One blastomere is removed Development continues Development continues 4 cell stage each blastomere is capable of regulating its development even when separated from the others Deuterostome Enterocoely blastocoel early mesodermal pouch ectoderm separation of pouches from gut endoderm developing coelom mesoderm Echinodermata Characteristics 1 Water Vascular System A system of coelomic canals that functions in circulation gas exchange excretion and locomotion stone canal madreporite ring canal radial canal tube feet Echinodermata Characteristics Water Vascular System ampulla podium The structure of the tube foot Tube feet Echinodermata Characteristics 2 Dermal Endoskeleton All echinoderms have a dermal endoskeleton that is composed of calcareous ossicles and is covered by epidermis The endoskeleton allows continuous growth and provides protection Fused to form a test e g sea urchins Articulating plates e g starfish Echinodermata Characteristics Dermal Endoskeleton In many echinoderms the skeleton bears spines or bumps that are used for defense Sea urchin Spines on crown of thorns starfish Echinodermata Characteristics Dermal Endoskeleton The epidermis covering the endoskeleton contains many specialized structures Dermal branchiae respiration an extension of the coelomic cavity Pedicellaria anti fouling Echinodermata Characteristics 3 Mutable connective tissue echinoderms can rapidly and reversibly change the stiffness of their connective tissue Echinodermata Characteristics 4 Secondary radial or biradial symmetry this bilaterally symmetrical larval form undergoes metamorphosis into an adult with radial pentamerous symmetry with 5 or more radiating areas bilateral larval stage radial pentamerous adult Feeding and digestion Grazers Predators Most species have a complete digestive system Nervous system circumoral nerve ring radial nerves Radial nerves no sense organs in most species except eyespots no cephalizaion no head circumoral nerve ring Nervous system anus radial nerves circumoral nerve ring mouth Echinodermata Characteristics Reproduction usually dioecious usually external fertilization eggs and sperm are shed into the water where fertilization occurs broadcast spawning indirect development with the presence of a free swimming bilateral larval stage some have direct development spawning sea urchins bilateral larval stage Phylum Echinodermata Class Asteroidea Class Echinoidea Class Ophiuroidea Class Holothuroidea Class Crinoidea Echinoderm Radiation anus Asteroidea aboral region arms oral region ambulacral region Echinodea fused ossicles Ophiuroidea Holothuroidea Crinoidea no ambulacral region no anus secondarily bilateral on a stalk feathery arms Class Asteroidea the sea stars ambulacral groove lined by tube feet madreporite mouth anus Aboral Oral Digestive gland cardiac stomach pyloric stomach gonads Class Echinoidea the sea urchins sand dollars heart urchins sea biscuits Class Echinoidea globular or disc shaped with no arms ossicle plates are fused to form a compact skeleton called a test ambulacral grooves closed movable spines with interspersed tube feet tube feet usually have suckers anus and madreporite aboral pedicellaria present Aristotle s lantern Class Echinoidea aboral where the spines attach aboral ambulacral region Class Echinoidea oral Inside the animal oral aboral oral Aristotle s lantern complex chewing mechanism 5 teeth are attached Sea Urchins are important grazers on reefs in sea grass beds and in Kelp forests Without urchins or with to many of them these
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