Biology Questions and Answers
Fishes
- What are the two main
classes into which fishes are
divided?
Fishes arclasses: chondrichthyes, fise divided into two mainhes with (^)
cartilaginodog-fishes), aus skeletons (sharks, rays,nd osteichthyes, bony
fishes (tuna, sardines, salmons).
- From which features do
condrichthyes and
osteichthyes get these names?
“Chondros” means cartilage, “ictis”
means fish name chondrichtians(both from the is for fishes withGreek); the
cartilaginous endoskeleton. The name
osteichthyof a bony endoskeleton es comes from thin these fishe existencees
(“osteo” means bone, from the Greek
too).
- What are the main features
of fishes associated to the
habitat where they live?
Fishes are all aquatic animals and thus
they havbody suitable to e a hydrodynamic elmove under water,ongated
without limbs anconditions the branchial resd with fins. Thpiration too.e habitat
- Comparing to cyclostomes
(primitive vertebrates) what
are the main novelties
presented by fishes?
Compared to cyclostomes,novelties presented by fishes ar evolutionarye:
pectoral anpaired; the presence of mandibles.d pelvic fins, symmetric and - How different are the
swimming strategies in
osteichthyes and in
chondrichthyes? Why do
sharks need to agitate their
body to swim while bony
fishes do not?
Bony fishes hcalled a gas bave a specializeladder, or swim blad organdder, (^)
whose interior can liberated from gas gbe filled with glands. The swimas (^)
bladder works as a hydrostatic organ
since it varies the relative dbody regulating buoyancy anensity od the depthf the (^)
of the animal in water.
Chondrichthyes dbladders and thus they musto not have swim
continuously agitate their bswimming and maintain their depth inody to keep
water. As an additional swimming aid, in
chondrichthyes ththis feature helps to re liver is beduce their bodyig and oily;
density relative to water.
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