Midterm Format

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Midterm Format

• Definition Short Answer)
• Answer 5 of 7
• 2 points each
• Total of 10 points
• Long Answer
• Answer 2 of 3
• 5 points each
• Total of 10 points

The midterm is worth 20 of your final grade.
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Biology of Fishes Midterm ZOOL 4170   Name
____________________________________________ Stude
nt Number ________________   The examination
will finish at 1220 p.m. Please read the
directions and questions carefully. You will be
asked to define 5 of 7 terms and answer 2 of 3
long answer questions. Answer in the space
provided (You may continue your answers on the
back of pages if necessary). Phrase all answers
in complete sentences.   1. Definitions (10
points - ONLY DEFINE FIVE TERMS)   a. Elasmobranch
ii         b. homocercal caudal
fin         c. pterygiophores
A subclass of class Chondrichthyes that includes
sharks and rays. Skeleton is made of cartilage,
though it may be calcified (no true bone). Gill
slits are uncovered and there is no gas bladder.
A cloaca is present.
An externally symmetrical tail fin that is
asymmetrical internally. One (or occasionally
two) vertebrae extend into the upper lobe of this
type of caudal fin.
Bones that provide support for medial fins in
teleost fishes. They are made up of proximal,
median, and distal elements. The proximal
elements insert between neural or hemal spines.
The distal elements articulate with the base of
the fins spine.
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2. ANSWER ANY TWO OF THE FOLLOWING QUESTIONS.
(5 Points each, 15 points total)   2a. Describe
the structures and processes of bioluminescence
in fish. Indicate its possible significance ,
with examples if appropriate.
Bioluminescence in fishes occurs in specialized
structures known as photophores. Light
production in most photophores is controlled
directly through nerve connections. Photophores
occur as two types 1) those harbouring symbiotic
bioluminescent bacteria and 2) those that produce
light within their own cells. In both types of
photophore, light is produced by the heatless
reaction of luciferin, ATP, and oxygen. In those
fish that produce their own light, luciferin may
be required from an external dietary sources,
such as is the case with the Plainfin Midshipman
(Porichthys notatus). Bioluminescence may be
significant to fishes for obtaining prey,
avoiding predation, or communication. These
could be accomplished through concealment,disguise
, mimicry, or advertisement. Ventral photophores
of deep water fish may assist in concealment by
braking up shadows formed against the light
background of the waters above. Luminescent
organs mimicing prey may attract other fish to be
fed upon. Fish may also use light to advertise
their presence in mating displays, to confuse
predators with their numbers, or to warn
potential predators of their dangers (such as the
venomous Atlantic Midshipman (Porichthys
plectrodon).