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WS 5.3 Finding Food, Avoiding Predators, & Mating in the Pelagic Ocean
Photic Zone Mating:
Fish Waves
Scientists have discovered an underwater phenomenon on a scale they've never seen before: a halfbillion herrings suddenly schooling together in the North Atlantic's Georges Bank.
For a week, a scientific team aboard research vessels used a new kind of sonar device to watch this
gigantic school form every evening. Makris described the nightly gathering as "city-states of fish."
Although many animals, such as birds or locusts, gather into flocks and swarms, Makris says this is the
first time an entire "chain reaction" that leads to swarming has been observed start to finish over such a large
area.
The process starts as fish begin to aggregate near the seabed at sunset. When the fish reach a critical
density — about one fish in a 15-foot-square area — their behavior changes. They draw closer to each other
into "clusters," Makris says, and align their movements. Then the clusters coalesce in what appears to be a
wave passing through the mass of fish. Makris says it looks like the kind of wave people create in sports
stadiums. "Somebody stands up," he says, "then somebody next to them stands up, and then the next and the
next, and before you know it you have a wave propagating from one end of the arena to the other." The
interesting thing about this motion is that just as in a stadium, the “group motion” travels a lot faster than any
individual in the group can go.
Once the giant school forms, it then moves south as a single entity, to an area where the fish spawn.
Princeton biologist Iain Couzin, who studies swarming animals, says, "It's important that they
synchronize their behavior to mate at the same time, to move together into particularly dangerous parts of the
oceans." The bigger the mass of fish, the less risk each fish has of getting eaten.
The mapping of this motion is particularly important in computer science. By analyzing and finding a
mathematical algorithm that mimics the herring school, it is believed that it can be applied to separate
computers trying to complete a single task. Just as in the fish school and stadium wave, this algorithm may be
able to organize many different computer to complete a single task through executing a small part of that task,
much faster than any one computer can accomplish it.
1. What is unique about herring schools?
2. Why are the herring schooling?
3. What are 2 reasons the hearing school?
4. What is the advantage of the herring being so large?
5. What are the reasons fish school?
6. What sense organs do fish use to school?
The Great Salmon Run
Salmon spend their early life in rivers, and then swim out to sea where they live their adult lives and
gain most of their body mass. When they have matured, they return to the rivers to spawn. Usually they return
with uncanny precision to the river where they were born, and even to the very spawning ground of their birth.
The eggs of a female salmon are called her roe. To lay her roe, the female salmon builds a spawning
nest, in the gravel of the streambed. The nest may contain up to 5,000 eggs, each about the size of a pea,
covering 30 square feet. The eggs usually range from orange to red. One or more males will approach the
female in her nest, depositing his sperm over her eggs. The males sperm will fertilize the egg cells. The
female then covers the eggs by disturbing the gravel at the upstream edge of the depression before moving on
to make another nest. The female will make as many as seven nests before her supply of eggs is exhausted.
After 2 to 6 months, the eggs hatch into tiny baby salmon, called fry. The fry have a sac containing the
remainder of the yolk, and they stay hidden in the gravel while they feed on the yolk. When the yolk has gone,
they must find food for themselves, so they leave the protection of the gravel and start feeding on plankton.
They remain in this stage for up to three years.
7. What type of reproduction (Ovi, vivi, or ovivivi) do the salmon use?
8. Why do the female salmon have so many eggs?
9. What is the word used to describe how salmon eggs are fertilized?
10. How can a fish undergo oviparous reproduction without broadcast spawning?
11. Describe the differences between a fertilized egg in oviparous reproduction and a embryo in viviparous
reproduction:
Oviparous:
Embryo is protected by:
Viviparous:
Embryo is protected by:
Embryo is fed by:
Embryo is fed by:
Dark zone mating:
12. What are the two challenges of mating in the deep ocean?
13. Describe two adaptations that help fish in the deep find each other to reproduce.
14. Why do some male fish attached themselves to females and become?
15. What is a hermaphrodite? Why is it an advantage to be a hermaphrodite in the deep ocean?
Dark zone Finding Food, Avoiding Predators
Identify the traits of a angler as a adaptation to attract prey or defend against predators and explain
why
16. Dark Color
a. Attract Prey or Defense
b. Why:
17. Large Mouth
a. Attract Prey or Defense
b. Why:
18. Light (Lure)
a. Attract Prey or Defense
b. Why:
19. What is a deep sea fishes bioluminescent organ most commonly used for if is located near the fishes
mouth or eyes?
20. What would be the purpose of bioluminescent organs not located near the mouth or eyes?
Photic zone Finding Food, Avoiding Predators
21. What can be determined from looking at the color of fish meat/muscle?
22. Why is there so little counter shading in deep water?
23. Why is there so little counter illumination in shallow water?
24. Name some sense organs do epipelagic fish depend on to hunt and for defense?
a.
b.
c.