Question 1

The ___________ ___________ was formerly thought to be a notochord.

Accepted Answer

buccal diverticulum

Question 2

Outline the phylogeny and adaptive diversification of the hemichordates and discuss the latest data of small subunit rRNA supporting a deuterostome phylogeny for this group.

Accepted Answer

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.

Question 3

________ ________ is a connective tissue that allows echinoderms to hold certain postures for long periods without straining muscles.

Accepted Answer

Catch collagen

Question 4

The hemichordates and echinoderms apparently form a sister group to the ________________.

Accepted Answer

The answer of The hemichordates and echinoderms apparently form a...

Question 5

The Class Enteropneusta are also known as __________________.

Accepted Answer

The answer of The Class Enteropneusta are also known as...

Question 6

The ancestor of the echinoderms had _____________ symmetry.

Accepted Answer

The answer of The ancestor of the echinoderms had _____________...

Question 7

The echinoids

Accepted Answer

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.

Question 8

Hemichordates live

Accepted Answer

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.

Question 9

The grooves that run along the oral side of the arms of sea stars are called ________________ grooves.

Accepted Answer

The answer of The grooves that run along the oral...

Question 10

The ossicles are penetrated by a meshwork of spaces filled with fibers and dermal cells; the meshwork is _____________ and is unique to echinoderms.

Accepted Answer

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

Question 11

Pedicellariae are

Accepted Answer

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.

Question 12

Brittle stars differ from sea stars by

Accepted Answer

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.

Question 13

The madreporite of sea cucumbers is located in the ________________.

Accepted Answer

The answer of The madreporite of sea cucumbers is located...

Question 14

The designation of hemichordates as primitive chordates in 1885 by Bateson has proved

Accepted Answer

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.

Question 15

Deuterostome characteristics

Accepted Answer

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

Question 16

Unique characteristics of echinoderms include all of the following EXCEPT

Accepted Answer

A)   an endoskeleton of plates or ossicles.
B)   marine, freshwater, and terrestrial species.
C)   pedicellariae.
D)   dermal brachiae.
E)   a water vascular system.

Question 17

Echinoderm evolution is controversial but most zoologists agree that ___________ are related and form one clade.

Accepted Answer

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.

Question 18

Describe the human response to the impact of sea star predators in oyster beds and include how the remedy for eliminating sea stars does not also eliminate the oysters.

Accepted Answer

The answer of Describe the human response to the impact...

Question 19

The function of the papulae in the sea star is

Accepted Answer

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

Question 20

Water enters the water vascular system of a sea star through a porous plate on the aboral surface called the

Accepted Answer

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

Exam 22: Chaetognaths, Echinoderms, and Hemichordates

The _ _ was formerly thought to be a notochord.