32 Questions
What is the main characteristic that gives the Cnidaria phylum its name?
The possession of cells called cnidocytes
Which organism is not a part of the Cnidaria phylum?
Ctenophores
What do cnidocytes contain that is characteristic of the Cnidaria phylum?
Nematocysts
What is the function of the organelles found in cnidocytes?
Defense mechanism
What is one of the striking aspects of the Cnidaria phylum?
Display of dimorphism and polymorphism
Which organisms may eat hydroids bearing nematocysts and use them for their own defense?
Ctenophores
What are the two morphological types that cnidarian forms fit into?
A polyp and a medusa
Which cell type is responsible for efficient predation in cnidarians?
Cnidocyte
What is the purpose of a nematocyst in cnidarians?
Injecting toxin for prey capture and defense
What is the function of an operculum in a nematocyst?
Covering the narrowed end of the capsule
What causes the discharge of a nematocyst in some sea anemones?
Tactile stimulation
What is the mechanism for nematocyst discharge in cnidarians?
Combination of tensional forces and high osmotic pressure
What is the characteristic body plan retained by both polyp and medusa forms of cnidarians?
Saclike body plan
Which type of cell produces over 20 kinds of distinctive organelles called cnidae?
Cnidocyte
What role does the trigger-like cnidocil play in cnidocytes?
Sensitizing to prey vibrations and causing discharge
What causes water to rush into the capsule of a nematocyst during discharge?
High internal osmotic pressure
What is the main function of the coelomic fluid in Phylum Annelida?
Supplying turgidity and functioning as a hydrostatic skeleton
What is the role of chitinous setae in Phylum Annelida?
Aiding in locomotion and providing sensory feedback
What is the characteristic nervous system structure in Phylum Annelida?
Double ventral nerve cord and a pair of ganglia with lateral nerves in each metamere
Which respiratory pigment is often present in the circulatory system of Phylum Annelida?
Hemoglobin
What is the primary site for excretory function in Phylum Annelida?
Nephridia
How do earthworms and freshwater worms differ from leeches with respect to chitinous setae?
Earthworms and freshwater worms have chitinous setae, while leeches lack them.
Which class of organisms is characterized by the presence of parapodia bearing tufts of many setae?
Class Polychaeta
Which class of organisms has a body with conspicuous segmentation and a spacious coelom usually divided by intersegmental septa?
Class Oligochaeta
Which class of organisms has a body with a fixed number of segments (normally 34) and oral and posterior suckers usually present?
Class Hirudinea
Which organism is commonly used as a type in introductory courses in Zoology?
Lumbricus sp.
What external feature distinguishes mature worms in the earthworm species?
Saddle-shaped enlargement called clitellum
What covers the body of Lumbricus sp., protecting it from physical and chemical injury?
Thin, transparent cuticle
What constitutes the outer tube of the earthworm's body, with the alimentary canal constituting the inner tube?
Body wall
What lies beneath the grooves in the earthworm's body, corresponding to an internal division of the coelomic cavity into partitions?
Septa
What part of the earthworm's digestive system lies in somites 1 to 3 and serves as a mouth cavity or buccal pouch?
Mouth cavity
What do the setae on segment or somite 26 become in mature worms, serving reproductive purposes?
Clitellum
Test your knowledge about the fascinating Cnidaria phylum, which includes sea anemones, jellyfish, corals, and other unique marine creatures.
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