Critical Thinking: ANOTHER Mass Update

Chapter 7
Cephalopods, the squids, octopuses, and allies, show a much higher degree of structural and behavioral complexity than the other groups of mollusks. What factors triggered the evolution of these changes? A rich fossil record among cephalopods shows that once they were very common and even dominant in some marine environments. Now there are only about 650 living species of cephalopods, far fewer than gastropods. In the end, were cephalopods successful? What do you think happened along the way?
Factors that triggered the evolution were the need for movement and a more active hunting lifestyle. Even though now they are sorely outnumbered, I think that cephalopods have been successful. That is why there are still around. The gastropods have such a soft body that they needed something hard to protect themselves, and because they carry around a protective shell, they have better protection. Cephalopods on the other hand, special in quick paced movement and have developed tactics to confuse or harm predators. Perhaps the reason that there are fewer species of cephalopods is because the weaker species have died off and those that are left are the dominant, successful species.

Chapter 9
Sea turtles have disappeared from many regions, and one way of trying to save them is to reintroduce them to areas where they have been wiped out. This is done by reburying eggs or by releasing newborn baby turtles on beaches. Why are eggs buried or baby turtles released instead of fully grown individuals?
By releasing newborns or burying eggs, the turtles will live a relatively "normal" turtle life. It is important for baby turtles to make their way down the beach and become familiar with it because years later they will migrate back to their birth location to lay eggs.

Chapter 18
Wastes from duck farms used to wash into two shallow-water bays on Long Island, New York. The wastes, rich in nutrients such as nitrate and phosphate, polluted the water. What do you think suppose was the immediate effect of the pollutants? Can you speculate on the likely effects on the comerically valuable shellfish of the area?
Since nutrients such as nitrate and phosphate are waste products, it did not have a very positive effect on the environment. Shellfish are filterfeeders and the waste in the water made them sick and it had an effect on the economy of the local area since no one wants to eat sick fish.

Coral Reefs: Part 2

Saipan is surrounded by irregular fringing reefs and a barrier reef off the lagoon. The fringing reefs are pink and the barrier reef isn't on the map, but it does exist in real life.


SIMILARITIES:
-all types of coral reefs
-need hard surface to grow
-all have reef slopes and reef flats
-variety of coral grow on reef slopes
-fish live in all the reefs

DIFFERENCES:
-barrier reefs and atolls have spur and grooves
-fringing reefs grow close to shore
-barrier reefs are separate by a lagoon and atolls surround lagoons
-fringing reefs can extend all the way to shore
-atolls are built on sunked volcanic islands

Adaptations in Biology

Reptilia
The saltwater crocodile has adapted to live in fresh water, salt water, or both (brackish or mixed water). Kidneys are crucial to help this remarkable feat, but they aren't the only way the croc accomplishes this; saltwater crocodile tongues have special glands that excrete salt. Another adaptation of saltwater crocodiles is that their eyes and nose are high on its head so that it can remain mostly underwater, hiding from its prey. Their broad tails and specially webbed feet help them swim and maneuver quickly. Like all crocodiles, saltwater crocs eat a variety of meat, anything they can get their hands on. Their powerful jaws are built to close quickly and tightly. With amazing jaw muscles, crocodiles hang on to their prey and perform the "death roll" to kill their victims. Like Steve Irwin always said, "Crikey!"

Saltwater Crocodiles

Aves
Penguins are awesome! These birds have been adapted to live in aquatic environments. Their wings are no longer used for flight, but rather make them very quick and agile in the water. Their feet are also webbed to assist in swimming, but this adaptation makes them waddle on land. Thankfully they look adorable. XP When they aren't waddling, they are most likely sliding along on their stomachs, which allows them to move rather quickly. Penguins keep themselves warm by a thick coat of waterproof feathers and a layer of blubber to insulate them against the frigid temperatures. One neat adaptation is their counter shading: they are light on their front side and dark on their front side. This way, when a penguin is swimming in the water, predators under them won't be able to see them against the light from the surface, and predators on top won't see them because they blend into the darkness of deeper water. Nifty little trick!

Penguin chick

Mammalia
Whales are mammals that disguise themselves as fish. Their bodies are streamlined, effective for life in the sea. Their tails are specially designed for movement and their flippers are paddle-shaped for maneuverability. Unlike fish, whales use lungs to breathe and must periodically come up to the surface for oxygen. Their lungs and bodies have been adapted to use as little oxygen as possible and whales can oftentimes stay underwater for hours at a time. Whales have a four-chambered heart, which allows them to efficiently circulate oxygen throughout their massive bodies. Whales also have a layer of blubber for insulation and an energy reservoir.

Baleen whale

Sea Floor in a Box

Coral Reefs: Part 1

1. How is each reef structure formed?
A fringing reef is formed when coral larvae settles on a hard surface and begins to grow. As the corals grow, they create their own hard bottoms, which creates a place for more coral to grow.
Barrier reefs are formed when sediment and coral rubble create a building foundation for the reef. Sea grass and seaweed beds, soft corals, and patches of cover coral are mixed in with the coral rubble to create a continuously growing bottom layer.
Atolls first start out as a fringing reef around a volcanic island. The reef gets wider and deeper as the island slowly sinks and eventually the reef flat becomes a lagoon and the fringing reef morphs into a barrier reef. When the island disappears completely the ring of growing reef left behind is the atoll.

2. Where is each reef structure found?
Fringing reefs are found on rocky shorelines close to land.
Barrier reefs, like fringing reefs, are found along the coast but farther out and separated by a lagoon.
Atolls are found on top of sunken volcanic islands which lie underneath a layer of calcium carbonate.

3. What is the trophic structure of a reef?
The trophic structure of reefs usually revolve around nutrient recycling. The zooanthellae take the coral nitrogen and phosphorus waste products and use the sun to create organic compounds which the corals need to survive. Without this process, corals would not be able to grow to their vast sizes since the water is usually poor in nutrients.

4. How does the location and type of reef influence the trophic structure?
Fringing reefs are close to shore so the water in which they live in gets run off and a mixture of nutrients and pollution from the land. Barrier reefs, however, are farther out so they have access to water from the lagoon and the deeper ocean. Additionally, the fish and other organisms that live in the reefs add and subtract from the nutrients in that community.

5. Give examples of the types of corals found on reefs.
Fast-growing corals, soft corals, hard corals, branching corals, TONS of corals!

6. Give examples of competition, predation, and grazing.
Competition is an overgrowth or direct attack of one coral to another in their fight for growing space. A Crown-of-Thorns starfish is an example of predation since it eats and completely kills coral. Many types of fish eat coral polyps, but they don't eat enough to kill the whole organism. Grazing keeps coral populations in check.

FRINGING REEF

BARRIER REEF

ATOLL

CRITICAL THINKING QUESTIONS: CHAPTER 14
1. What factors might account for the fact that the vast majority of atolls occur in the Indian and Pacific oceans and that atolls are rare in the Atlantic?
Temperature is the reason why atolls are found in the Indian and Pacific Oceans. The Atlantic is just too cold for coral reefs to grown in. The Pacific Ocean is also filled with volcanic activity. Atolls occur after the coral reefs build up on volcanic sentiment. The Atlanic's environment is simply not conducive to the needs of atolls.
2. Scientists predict that the ocean will get warmer and the sea level will rise as a result of an intensified greenhouse effect. How might this affect coral reefs?
Coral reefs need temperate waters to thrive. If the ocean gets too warm, all the corals will die. If the ocean gets too deep, the sunlight won't be able to penetrate the water and all the corals will die. It's a lose-lose situation really.
3. There are only a few reefs off the northeast coast of Brazil, even though it lies in the tropics. How would you explain this?
The northeast end of Brazil is located in water temperatures ideal for coral reef growth. However, the northeast end of Brazil is also located near the mouth of the Amazon River, which has a direct affect on the salinity, sediment, and pollution levels. Corals cannot thrive in water that has too little or too much salt. Silt blocks the sunlight needed for coral growth. Pesticides and other wastes harm the corals as well.

Critical Thinking: Chapter 2

2. Why are most oceanic trenches found in the Pacific Ocean?
Most of the trenches are found in the Pacific Ocean because the western part of the Pacific Plate (closest to Asia) is colliding with the Eurasian, Philippine, and other smaller plates. In the force of the collision, the Pacific Plate is moving downward under the other plates forming trenches (or subduction zones) across the various plate borders.
In the Atlantic Ocean, the North American, Eurasian, South American, and African Plates are not colliding but rather spreading apart from each other; so no trenches are formed.

Sea Floor Spreading Stuff

What is sea floor spreading?

The process by which new sea floor is formed as it moves away from spreading centers in mid-ocean ridges.

What are some of the major land forms that are created from plate movement?

Mountains, volcanoes, trenches, and the 7 continents were all formed from plate movement.

How were the Mariana Islands formed?

The Marianas were formed by volcanoes. Nowadays they are most dormant, but occasionally one will erupt, spreading sulfur up into the atmosphere and over the other islands.

What evidence exists today that the plates are still moving and that the islands are ancient volcanoes?

As I mentioned earlier, there are still active volcanoes in Micronesia, and which the continous earthquakes, we know that the plates are still in motion.

What is an atoll?

A product of a reef; often islands or sand cays surrounding a central lagoon.

Why are atolls mainly found on the Pacific?

Atolls grow on coral reefs, which are found mainly in the Pacific Ocean because of the warm climate.