The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk, and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, do not molt (though their host does), and their embryos undergo spiral cleavage.
Which of these features is least useful in assigning the phylum Cycliophora to a clade of animals?
A) having a true coelom as a body cavityB) having a body symmetry that permits a U-shaped intestine
C) having embryos with spiral cleavage
D) lacking ecdysis (molting)
Answer: A
Basing your inferences on information in the previous paragraph, to which clade(s) should cycliophorans belong?
1. Eumetazoa2. Deuterostomia
3. Bilateria
4. Ecdysozoa
5. Lophotrochozoa
A) 1 only
B) 1 and 3
C) 1, 3, and 5
D) 2, 3, and 4
E) 2, 3, and 5
Answer: C
If harboring large populations of cycliophorans neither helps nor harms their lobster hosts, then cycliophorans can be properly considered to be
1. parasites.
2. mutualists.
3. commensals.
4. symbionts.
5. endosymbionts.
A) 1 and 4
B) 2 and 4
C) 3 and 4
D) 2 and 5
E) 3 and 5
Answer: C
On the basis of the cleavage pattern of cycliophoran embryos, which of these should be true?
A) It has determinate development.
B) The blastopore becomes the anus.C) They are deuterostomes.
D) A cell separated from a four-cell embryo should develop into a complete organism.
Answer: A
Using similarities in embryonic development, body symmetry, and other anatomical features to assign an organism to a clade involves
1. cladistics based on body plan.2. molecular-based phylogeny.
3. morphology-based phylogeny.
A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1 and 3
Answer: E
Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?
A) if the ciliated feeding ring is a lophophoreB) if embryos are diploblastic
C) if the body cavity is actually a pseudocoelom
D) if the organisms show little apparent cephalization
Answer: B
What is true of the feeding stage of cycliophorans?
1. It is chemoheterotrophic.
2. It is sessile.
3. It captures food in a manner similar to that of animals with lophophores.
4. It has radial symmetry.
A) 1 and 2
B) 1 and 3
C) 2 and 4
D) 1, 2, and 3
E) 2, 3, and 4
Answer: D
Cycliophorans have two types of larvae. One type of larva is produced when the digestive system of a female is impregnated by a male. The digestive system then collapses and develops into a larva, which swims away in search of a new host after the surrounding female dies. Which is the embryonic tissue that is apparently most important in forming this type of larva?
A) mesohylB) mesoderm
C) ectoderm
D) endoderm
E) mesoglea
Answer: D
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