16.7: Adaptations to the Marine Environment

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Miracosta Oceanography 101
Miracosta)

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Adaptations to the Marine Environment

• Ability to float (Zooplankton – some produce fats or oils to stay afloat)
• Ability to swim (Nekton – larger fish and marine mammals)

Propulsion and movement of fish - the body plan of fish reflect adaptations to feeding on prey and fleeing predators.

Width/Length Ratio

Tuna - .28
Dolphin - .25
Swordfish - .24
Whale - .21

Most efficient is about.25, but there is a size-scale factor.
Ratio produced from natural selection “the fittest survive and produce offspring”

Compare with Surfboard Design!

Type	Width	Length	Ratio	Comments
Short Board	19 ¼"	6’4”	0.25	Small – medium waves
PT (Ebenizer Townsend, 1798)	19 ¼"	6'7"	0.24	Large waves
Average Long Board	22"	9'0"	0.20	Like a whale – scale factor
Average Surf Board	18 ¼"	6’2”	0.25	rapid turns, harder to control

Kinds of Zooplankton

Includes organisms described as floaters and drifters. All forms are invertebrates.
Microscopic Zooplankton include:
Radiolarians, Foraminifers, Copepods

Macroscopic Zooplankton:
• Krill ( resemble mini shrimp or large copepods, critical in Antarctic food chains)


Figure 16.43. Copepods	Figure 16.44. Krill

Floating Macroscopic Zooplankton include:

• Portuguese man-of-war (have gas-filled float)
• Jellyfish (have soft, low-density bodies; there are hundreds of species)

Many species of portuguese man-of-war and jellyfish can sting or produce potent toxins.


Figure 16.45. Portuguese man-of-war	Figure 16.46. Jellyfish

Swimming (Nekton) Organisms

Includes all fish, squids, sea turtles and sea snakes, and marine mammals.

• Swim by trapping water and expelling it (squid, octopus)
• Swim by curving body from front to back (fish, etc.)

Adaptations for Finding Prey

• Lungers wait for prey and pounce (grouper).
• Cruisers actively seek prey (tuna).


Figure 16.48. Groupers are lungers	Figure 16.49. Tuna are cruisers

Adaptations to Avoid Predation
• Speed
• Hiding: includes Transparency, Camouflage and Countershading
• Poison (to touch or eat: examples: sea snakes, blowfish, lion fish)
• Schooling (safety in numbers, appear as a larger unit, maneuvers confuse predators)

Figure 16.50. Lionfish are highly poisonous.

Video: Schooling anchovies at Scripps Pier (Scripps Institute of Oceanography)