Thursday, November 29, 2007

Critical Thinking Questions: Mass Re-Collection Part 2

Critical Thinking

Chapter 7

  1. Cephalopods, the squids, octopuses, and allies, show a much higher degree of structural and behavioral complexity then the other groups of molluscs. 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?

For any amount of evolutionary advancement to such a height in the structural and behavioral complexity of the cephalopods, would require millions of years and several processes of natural selection. My hypothesis on this evolutionary achievement would be either that they were, at one point, at a disadvantage and had to rely on other ways to either obtain food and/or to defend themselves against predators. Yet, in accordance to the fossil record, which in the question states that, “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 that the several species of cephalopods may have died out due to the mass extinction several millions years ago, and that those that survived, may have more species die out because of the competition between one another for food; it is here where my hypothesis may come into play. But in terms of their success, it is both a negative and positive one, for in terms of their diversification, it is a negative because of the amount of species that are currently living today; yet, it is also a positive because of their structural and behavioral complexity that they have gained through the millions of years of natural selection.

Chapter 9

1. 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 reburied or baby turtles released instead of fully grown individuals?

According to several theories on how sea turtles find their birth place to lay eggs, though they spend majority of their lives hundreds of miles away from it, is due to the magnetic field that has imprinted itself in their brain during incubation and/or hatching. Therefore, it would be best that the eggs would be reburied instead of re-introducing adults to a new beach.

Chapter 18

  1. Wastes from duck farms used to wash into two shallow-waters bays on Long Island, New York. The wastes, rich in nutrients such as nitrates and phosphate, polluted the water. What do you suppose was the immediate effect of the pollutants? Can you speculate on the likely effects on the commercially valuable shellfish of the area?

Because of the rich chemicals that contaminated the bay from the results of run-off, there will be two immediate consequences: 1. all the organisms sensitive to slight environmental changes will die quickly and the remaining surviving organisms will be forced to move, 2. those organisms that survive may go through the event of a population explosion where competitive exclusion takes place and later, because of the shortage in the amount of food consumed by the dominant organism, they may die and be forced to move as well.

The shellfish, being greatly affected by the poisoning of the water by nitrate and phosphate rich chemicals through run-off because of their filter feeding properties as a way to capture food, will absorb a great amount of unneeded nutrients making them far too dangerous to consume thus ruining the several shellfish businesses.

Fishy slides

Wednesday, November 28, 2007

Coral Reefs: Part 2

Map info. courtesy of Taylor
-all types of coral reefs
-need hard surface to grow
-all have reef flats, reef slopes, and reef crests
-variety of coral grow on reef flats and reef slopes
-fish live in all the reefs

-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
-no atolls due since Saipan is a raised-limestone island

Coral Reefs: Part 1

1. How is each reef structure formed?
Coral reefs begin to form when free-swimming coral larvae attach themselves to submerged rocks or other hard surfaces along the edges of islands/continents. As the corals grow and expand, reefs take on one of three major characteristic structures —fringing, barrier or atoll.

  • Fringing reefs, which are the most common of all reefs, project seaward directly from the shore, forming borders along the shoreline and surrounding islands. Fringing reefs also grow on soft bottoms if there is even a small hard patch that lets the corals get a foothold. From there, the corals slowly creates their own hard bottom and expand themselves.
  • Barrier reefs also border shorelines, but at a greater distance - sometimes as far as 100km. They are separated from their adjacent land mass by a lagoon of open, often deep water. The barrier reef consists of a back-reef slope, a reef flat, and a fore-reef slope, which corresponds to the reef slope of a fringing reef and has a reef crest.
  • If a fringing reef forms around a volcanic island that subsides completely below sea level while the coral continues to grow upward, an atoll forms. Atolls range in size from small rings less than a mile across to systems well over 30 km in diameter.

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 revolves around nutrient recycling - which is basically zooxanthellae dependent since they are the dominant primary producers in the ocean. They 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 runoff of 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.
Common Name:
Branching Corals
Scientific Name:
Acropora Sp.

Type of Reef found on:
Reef Flat
Key Identification:
Stick like appearance & branching,
usually in colonies

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.

Critical Thinking

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?

Since corals are temperature dependent and nutrient dependent, they would most likely be found in the Indian and Pacific Oceans. Besides that, because of the Ring of Fire's location in the Pacific Ocean, atolls only be found there.

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?

Disastrous effects may happen due to the amount of green house gases released. With a huge amount of CO2 released into the atmosphere, it not only destroys the ozone layer, which would allow infrared heat to get trapped in the Earth’s atmosphere, causing the polar regions to melt thus allowing the sea level to rise; but, because of gas exchange, it would devastate the living organisms in the ocean. The vast amount of dissolved CO2 would increase the amount of hydrogen carbonate ions, which in the overall process, would increase the acidity of the ocean (pH level) and retard the growth of corals because of the secondary buffer produced by the hydrogen carbonate ions – therefore diminishing the number of calcite ions, which are needed to combine with calcium carbonate ions that are needed to make exoskeletons. As for the living corals, they may die out too because of all the stress they would be receiving from the fluctuated environment (coral bleaching).

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 reason why there are no coral reefs by the northeast coast of Brazil is because the Amazon River empties out there. The Amazon River carries silt which contributes to a murky appearance. Because of that, coral reefs could not be supported since sunlight wouldn't be able to reach the bottom.

Friday, November 16, 2007

Sea Floor Spreading

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 Mariana Islands were formed by underwater volcanoes along the Marianas Trench. The northern islands consist of high volcanic islands while the southern islands consist of raised-limestone.

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

The frictional movement of the Philippine plate under the Pacific plate above the asthenosphere which causes earthquakes and minute tremors.

What is an atoll?

An atoll is a coral reef that develops as a ring around a central lagoon.

Why are atolls mainly found on the Pacific?

Atolls establish themselves on coral reefs, which are found mainly in the Pacific Ocean because of its warm tropical climate.

Chapter 2: Critical Thinking

4. What are some of the major pieces of evidence for the theory of plate tectonics? How does the theory explain these observations?

According to Wegner’s hypothesis, which suggests that all continents had once been joined in a single “supercontinent,” named Pangea, the theory of plate tectonics was developed – a process that involves the entire surface of the planet. This theory is constituted of several evidences such as:

  • Coal-deposits and other geological formation on either side of the Atlantic match exactly
  • Fossils on opposite sides of the ocean that exactly match
In regards to Wegner's hypothesis on continental drift, as well as the theory on plate tectonics, it is quite obvious that the evidences stated above are true, since the fossil records on biotic and abiotic life supports it.

Tuesday, November 13, 2007

Adaptations and Biology of Birds, Reptiles, and Mammals

Saltwater crocodile
The saltwater crocodile can live in fresh water, salt water or brackish (mixed) water. If it is living in salty water, its kidneys and tongue allows the excretions of salt. It has eyes and nostrils high up on its head and a broad tail with webbed feet for swimming. It feeds on almost any meat it can get. Animals that live in the water and near the water may/will become food for the saltwater crocs - even people!! A hunting tactic that it has developed includes the art of camouflage - where it stealthily moves underwater with only its nostrils above the surface. Besides the saltwater crocodile's art of stalking its prey, it also has its elusive death roll that it uses in order to tear flesh which gives an instantaneous death when clamped between both jaws.

Penguins are superbly adapted to an aquatic life. Their wings have become flippers - and contain a denser bone material that is useless for flight in the air, in water however, penguins are astonishingly agile. Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance. All penguins are countershaded - that is, they have a white underside and a dark (mostly black) upperside. This is for camouflage. A predator looking up from below (such as an orca or a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above. Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17 mph) (which are more realistic in the case of startled flight). The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Dives of the large Emperor Penguin have been recorded which reach a depth of 565 m (1870 ft) and last up to 22 minutes. Penguins either waddle on their feet or slide on their bellies across the snow, this allows them to conserve energy and move relatively fast at the same time. They also jump, with both feet together. Penguins have an excellent sense of hearing. Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air, conversely, they are nearsighted. Their sense of smell has not been researched so far. They are able to drink salt water safely because their supraorbital gland filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.

Baleen Whale
Like all mammals, whales: breathe air into lungs, are warm-blooded, feed their young milk from mammary glands, and have some hair. The body is fusiform, resembling the streamlined form of a fish. The forelimbs, also called flippers, are paddle-shaped. The end of the tail fins provide propulsion by vertical movement. Most species of whales bear a fin on their backs known as a dorsal fin. Beneath the skin lies a layer of fat. It serves as an energy reservoir and also as insulation. Whales have a four-chambered heart. The neck vertebrae are fused in most whales, which provides stability during swimming at the expense of flexibility. Whales breathe through blow holes located on the top of the head so the animal can remain submerged. Whales have a unique respiratory system which allows them to stay underwater for a long period of time without needing to re-surface to breathe. There are similarities between the ears of whales and humans, whales’ ears have specific adaptations to their underwater environment. In humans, the middle ear works as an impedance matcher between the outside air’s low-impedance and the cochlear fluid’s high-impedance. In aquatic mammals such as whales, however, there is no great difference between the outer and inner environments. Instead of sound passing through outer ear to middle ear, whales receive sound through their lower jaw.