Swimming Modes

swim like “airplanes”

cartilaginous fish

swim in a “waving” motion (jerking back and forth)

teleosts

1. trunk/tail

2. tail (caudal fins)

3. fins

3 primary propulsion sources (combinations are possible)

movement in Chondrichthyes

• flexible spines/skeletons allow for “bendiness” (useful for last second adjustments)

• entire body used for swimming “body-based swimming”

• girdle-fin connections force “one-way” movements

• can only swim forward

movement in teleosts

• bones are ossified, inflexible and rigid

• girdle-fin connections allow for fins to move independently, allowing for fine-scale movements

• can swim in any direction

• combination of “body-based” and “fin-based” swimming

anguilliform movements

moves by “slithering” trunk and tail (head stays still)

example→ eels

thunniform movements

moves by tail (caudal) fin only, trying to keep head as still as possible

example→ tunas

trunk/tail movements

the more the movement comes from the tail, the GREATER the MAX SPEED

example→ salmonids and gadiforms

fin-based swimming

• medial fins (dorsal/anal)

• pectoral/pelvic

• fins can move in 2 ways: undulation or oscillation

• provide fine-scale movements for rigid skeletons

undulation

fins move in a wave pattern

oscillation

fins move in a back and fourth pattern

anguilliform movements present in fish with long bodies (eels) and thunniform movements present in fish with fusiform bodies (tunas)

how is locomotion linked to body shape?

body shapes

if fins do the work, the fish can have a variety of _______ that often live in structured habitats (coral reefs) or on the bottom of their watershed

they mainly use anguilliform movements but some use more of their trunk/tail

what about sharks?