Fishs & Adaptations

Question 1

What is Nekton?

Answer 1

Organisms capable of sustained locomotion against the motion of water
Opposite of plankton
Can be divided into 2 main groups (holo epipelagic, and mero epipelagic)

Question 2

Holo Epipelagic

Answer 2

Organisms spend their entire lives in the epipelagic (upper part of the ocean)

EX. Whale shark, marlins, tuna, etc.

Question 3

Mero Epipelagic

Answer 3

Organisms spend only part of their lives in the epipelagic
They usually come up to the upper parts of the ocean to spawn and feed

EX. Lanternfish, barreleye fish, sabertooth fish, etc.

Question 4

Fish Adaptations : Buoyancy

Answer 4

The most significant adaptation of fish is that which keeps the organisms suspended or buoyant in the water column

Question 5

Bony Fish Buoyancy

Answer 5

Most have swim (gas) bladders, in which they can regulate the amount of gas to help regulate their position in the water column

Question 6

Shark Buoyancy

Answer 6

Do not have swim bladders, instead store oil from the fish they consume as well as using a constant swimming motion to stay afloat

Question 7

Fish Adaptations : Locomotion

Answer 7

The adaptations of fish related to moving through the water fall into 2 main categories
- Creation of propulsive force (tail shape)
- Reduction of frictional resistance and drag (body and fin shape)

Question 8

Fast Swimming Fish

Answer 8

Typically have a fusiform body with a lunate tail
The speed is generated by muscle contraction waves that pass down the body

Question 9

Slow Swimming Fish

Answer 9

Typically have a deep and laterally compressed body with a broad paintbrush tail

Question 10

Fusiform Body

Answer 10

Thin, long, hydrodynamic body

Question 11

Lunate Tail

Answer 11

Deeply forked tail

Question 12

Fish Adaptations : Defense & Camouflage

Answer 12

Camouflage is the most common defense mechanism in fish
There are 2 main ways in which fish use camouflage
- Cryptic coloration
- Countershading

Question 13

Cryptic Coloration

Answer 13

Often involves a blending of colors to match the background of the organism
Typically prey

Question 14

Countershading

Answer 14

Often involves lighter colors on the ventral side and darker shading on the dorsal side
Typically predator

Question 15

Fish Adaptations : Sensory Systems

Answer 15

Most sensory systems that fish have evolved are similar to those seen in land animals

Question 16

Lateral Lines

Answer 16

All fish have this
Sensitive to pressure changes in the water
Allows fish to school

Question 17

Ampullae of Lorenzini

Answer 17

Sharks and rays have this
Sensitive to minute electrical currents in the hearts of other organisms

Question 18

Fish Adaptations : Reproduction

Answer 18

There are 5 reproductive strategies used by fish:
* Ovuliparity
* Oviparity
* Ovoviviparity
* Viviparity
* Hermaphroditism

Question 19

Ovuliparity

Answer 19

Also known as “broadcast spawning”
Female and male fish release gametes in to the water at the same time

Question 20

Oviparity

Answer 20

Fertilization occurs internally and then the female releases the recently fertilized eggs into the water
Est. about 97% of fish reproduce this way

Question 21

Ovoviviparity

Answer 21

Fertilized eggs develop internally using yolk sacs within the female fish
Live young are then expelled

Question 22

Viviparity

Answer 22

Embryos develop internally and nutrients are received via tissues or blood from the female

Question 23

Hermaphroditism

Answer 23

Occurs when a species of fish contains both male and female reproductive organs, or can alternate possession one and then the other

Question 24

Marine Reptiles

Answer 24

All marine reptiles evolved on land and have since returned to the sea
Only one species of crocodile (giant saltwater crocodile) and one species of lizard (marine iguana)
There are many species of sea snakes and sea turtles

Question 25

Sea Turtles

Answer 25

There are 7 species of sea turtle, ALL of which are classified as endangered or threatened
Sea turtles use a geomagnetic sensory system (use the magnetic poles of Earth to migrate)
Female sea turtles lay their eggs at the same location they were born, year after year
Sea turtle eggs hatch as either male or female depending on the temperature of the sand

Cooler sand —-> Male
Warmer sand —-> Female

Question 26

Threats to Sea Turtles

Answer 26

Entanglement in fishing gear (bycatch)
Poaching, illegal trade of eggs, meat, and shells
Coastal development
Plastic and other marine debris
Global warming
Ocean pollution

Question 27

Pinnipeds

Answer 27

Include seals, sea lions, and walruses
They are divided into 3 groups:
* Odobenidae
* Otariidae
* Phocidae
Typically prefer cold waters
Almost all have fur coats

Question 28

Odobenidae

Answer 28

Walrus

Question 29

Otariidae

Answer 29

“Eared seals”
Sea lions
Fur seals

Question 30

Phocidae

Answer 30

“Earless seals”
True seals