Did the single gastric opening evolve into a mouth, with the anus forming elsewhere in the body (protostomy), or did it evolve into an anus, with the mouth forming elsewhere (deuterostomy), or did it evolve into both mouth and anus (amphistomy)? These questions are addressed by the comparison of developmental fates of the blastopore, the opening of the embryonic gut, in diverse animals that live today. However, there is no consensus on how this happened. Allow water to exit after food has been gathered from the inflow The excretory system of an enteropneust hemichordate (or acorn worm) consists of.It is widely held that the bilaterian tubular gut with mouth and anus evolved from a simple gut with one major gastric opening. Water to be drawn in to stiffen the chambers to aid in burrowing The gill slits of enteropneust hemichordates function to. Both the echinoderms & the chordates The pores leading to both the protocoel & paired coelomic cavities of the enteropneust hemichordates allows. have secretive habits & fragile bodies Hemichordates show relationships to. In deep oceans, especially the rich & oxygenated Arctic Ocean Hemichordates were not recognized until the 1800s because they. Crinoids & sea urchins The designation of hemichordates as primitive chordates in 1885 by Bateson had proved Overenthusiastic since the structure. All of the choices correct The crinoids All correct Echinoderms evolution is controversial but most zoologists agree that _ are related & form one clade. Modified tube feet The respiratory tree of a sea cucumber is. Aristotle's lantern The oral tentacles of the sea cucumber are. Are enclosed in an endoskeleton test or shell The complex chewing apparatus found in many sea urchins is the. Respiration & Reproduction The echinoids. Having the ambulacral grooves closed & covered with arm ossicles The five pairs of bursae in brittle stars are used for. A somatocoel Brittle stars differ from sea stars by. Larval form of many echinoderms In enchinoderms, the main coelomic compartment is. Sexually, usually with separate sexes "Bipinnaria" describes the. Still not known for certain Sea stars reproduce mostly. Stone & ring canals The role of the hemal system is best described as. A sea star feeds by absorbing food through the. A simple nerve ring & radial nerves leading to simple sensory cells scattered over the epidermis. Pyloric ceca that produce digestive fluids for extracellular digestion How much nervous system does an echinoderm have? Sea stars have. Part of the function of tube feet is hydraulic & part is controlled by the nerve stimulation Structures in each arm of a sea star include the gonads, the system that works the tube feet, and. Ossicles The ossicles are penetrated by a meshwork of spaces filled with fibers & dermal cells the meshwork is _ & is unique to echinoderms Stereom If you went to the ocean & brought back a sea star to keep in a marine aquarium, what would you feed it? Live clams How do the tube feet of sea stars & sea urchins operate? A hydraulic system regulates water pressure in the tube feet Which is NOT a correct association of structure & function in sea star anatomy? Ampulla-end of the tube foot that bears the sucker If the radial nerve in an arm is cut. Madreporite or Sieve plate The calcareous plates found underneath the epidermis are called the. Respiration Water enters the water vascular system of a star through a porous plate on the aboral surface called the. The function of the papulae in the sea star is. Small pincer-like projections clustered on the skin of a sea star. Tube feet run along the _ groove that extends along the oral side from the mouth to the tip of each arm.
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