Exam 22: Chaetognaths, Echinoderms, and Hemichordates

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buccal diverticulum

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A) Pyloric ceca
B) Radial canals
C) Polian vesicles
D) Coelomocytes
E) Stereom

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A) lacking pedicellariae.
B) lacking papulae, intestine, or an anus.
C) having the ambulacral grooves closed and covered with arm ossicles.
D) having tube feet without suckers.
E) all of the choices are correct distinctions.

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A) larval sea stars.
B) the mouth-like openings into the center of the bottom of the sea star.
C) structures linking the madreporite and the ring canal.
D) small pincer-like projections clustered on the skin of a sea star which serve to keep it clean of parasites and aquatic growth.
E) soft and delicate projections of the coelomic cavity covered with epidermis.

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A) in the open ocean with a similar lifestyle to arrow-worms (which is why they are considered related) .
B) in kelp beds.
C) in deep oceans, especially the rich and oxygenated Arctic Ocean.
D) on the bottom of shallow oceans, sometimes colonially and in secreted tubes.
E) just around thermal vents.

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Hemichordates are a group of marine invertebrates that are closely related to chordates, which include vertebrates. The phylogeny of hemichordates has been a topic of interest for researchers, as it provides insights into the evolutionary history of deuterostomes, a major group of animals that includes vertebrates. The phylogeny of hemichordates is characterized by their adaptive diversification into three main classes: Enteropneusta (acorn worms), Pterobranchia, and Planctosphaeroidea. These classes exhibit a wide range of body plans and ecological adaptations, reflecting their diverse evolutionary history. Recent data from small subunit rRNA sequences have provided support for a deuterostome phylogeny for hemichordates. This molecular evidence suggests that hemichordates share a common ancestor with echinoderms, another group of deuterostomes that includes sea stars and sea urchins. This finding is consistent with morphological and developmental similarities between hemichordates and echinoderms, such as the presence of gill slits and a tripartite body plan during embryonic development. Overall, the phylogeny and adaptive diversification of hemichordates provide valuable insights into the evolutionary history of deuterostomes. The latest data from small subunit rRNA sequences support a deuterostome phylogeny for this group, shedding light on their evolutionary relationships with other major animal groups.

A) accurate using new molecular data.
B) overenthusiastic since the structure he interpreted as a notochord does not have notochord embryology.
C) completely wrong since new research indicates that all features he interpreted as chordate features are actually other structures.
D) as puzzling today as in 1885.
E) None of the choices are correct.

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A) have five long, slender arms.
B) are enclosed in an endoskeletal test or shell.
C) lack tube feet.
D) lack ambulacral areas.
E) are unable to move because of their spines.

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The human response to the impact of sea ...

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A) sea stars and brittle stars.
B) sea stars and sea urchins.
C) sea stars and sea cucumbers.
D) sea urchins and sea cucumbers.
E) crinoids and sea urchins.

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Catch collagen

A) Aristotle's lantern.
B) Pedicellariae.
C) Madreporite or sieve plate.
D) Pedicellariae
E) Ambulacrum.

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A) Mouth develops from or near the blastopore
B) Coelom budded off from the archenteron
C) Radial and regulative cleavage
D) Mesoderm derived from or with the endoderm from enterocoelic pouches

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A) Respiration
B) Excretion
C) Reproduction
D) Digestion
E) Defense and protection

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