Chapter 9 Critical Thinking

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?

Maybe because new born and/or eggs would be more effective to reproduce again...the old turtles may be more relaxed and unable to reproduce. The only thing about reburying eggs is that other species may eat the egg which leads to no baby turtles.

Chapter 1 Critical thinking

2.) In Chapter 1 it was expalined that the statement "There are mermaids in the ocean" is not a valid scientific hypothesis. Can the same be said of the statment "There are no mermaids in the ocean"? Why?

-->The statement, "There are no mermaids in the ocean", is not a valid scientific hypothesis, because it is not testable. This statement cannot be potentially proven to be false. Even if an army of marine biologists were to spend their entire career looking for a mermaid, the ocean is far too large for such a study. There may be some comments on individuals seeing a mermaid...then again people say things to noticed or known...proof would be the first step to proving the statement, "There are no mermaids in the ocean" or "there are mermaids in the ocean". As for now no hard core evidence to prove both these statements.

Chapter 3 Critcal Thinking

4.) Most tsunamis occur in the Pacific Ocean, as indicated by the map in the "Waves that Kill" boxed reading. How would you explain this?-->Tsunamis are caused from earthquakes, landslides, volcanoes, and other seismic disturbances of the sea floor. Unfortunately, 85% of all tsunamis occured in the Pacific Ocean. Around the rim of the Pacific Ocean are many volcanoes. This is known as the Pacific Rim of Fire. These eruptions are one of the main causes of the seismic activity in the Pacific Ocean.

Chapter 2 Critical Thinking

2.) Why are most oceanic trenches found in the Pacific Ocean?-->An oceanic trench is a linear depression of the sea floor caused by the subduction of one plate under another. These trenches are associated with earthquakes and volcanoes. They are generally parallel to a volcanic island arc. Examples include are the Mariana Islands which are located in the Pacific Ocean.

Oceanic trenches typically extend 3 to 4 km below the level of the surrounding oceanic floor. The deepest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench at a depth of 10,911 m (35,798 ft) below sea level.

Squid

a.) Digestive System: Squid, like all cephalopods, have complex digestive systems. Food is transported into a muscular stomach, found roughly in the midpoint of the visceral mass. The bolus is then transported into the caecum for digestion. The caecum, a long, white organ, is found next to the ovary or testis. In mature squid, more priority is given to reproduction and so the stomach and caecum often shrivel up during the later stages of life. Finally, food goes to the liver (or digestive gland), found at the siphon end of the squid, for absorption. Solid waste is passed out of the rectum. Beside the rectum is the ink sac, which allows a squid to discharge a black ink into the mantle cavity at short notice.
http://en.wikipedia.org/wiki/Squid#Digestive_system

b.) Circulatory System: The circulatory system is open, except in Cephalopoda and usually includes a dorsal heart with one or two atrias and one ventricle. This is situated in a pericardial cavity. An anterior aorta and other vessels and many blood spaces (hemocoels) exist in the tissues.
http://marinebiology-shine.blogspot.com/2007_10_01_archive.html

c.)Nervous System: The giant axon of the squid, which may be up to 1 mm in diameter, innervates the mantle and controls part of the jet propulsion system.
http://en.wikipedia.org/wiki/Squid#Digestive_system

d.) Excretory System: Squid have three hearts. Two branchial hearts, feeding the gills, each surrounding the larger systemic heart that pumps blood around the body. The hearts have a faint greenish appearance and are surrounded by the renal sacs - the main excretory system of the squid. The kidneys are faint and difficult to identify and stretch from the hearts (located at the posterior side of the ink sac) to the liver. The systemic heart is made of three chambers, a lower ventricle and two upper auricles.
http://en.wikipedia.org/wiki/Squid#Digestive_system

e.) Reproductive System: In female squid, the ink sac is hidden from view by a pair of white nidamental glands, which lie anterior to the gills. There are also red-spotted accessory nidamental glands. Both of these organs are associated with manufacture of food supplies and shells for the eggs. Females also have a large translucent ovary, situated towards the posterior of the visceral mass.Male squid do not possess these organs, but instead have a large testis in place of the ovary, and a spermatophoric gland and sac. In mature males, this sac may contain spermatophores, which are placed inside the mantle of the female during mating.
http://en.wikipedia.org/wiki/Squid#Digestive_system

f.) Integumentary System: The integumentary system of a squid is enclosed in the mantle, which has two swimming fins along each side. These fins are not the main source of their motility. The skin of the squid is covered in chromatophores, which allows the squid to change color to suit its environment. The underside of the squid is also found to be lighter than the topside, in order to provide camouflage from both prey and predator (countershading).Under the body are openings to the mantle cavity, which contains the gill and openings to the excretory and reproductive systems. At the front of the mantle cavity lies the siphon, which the squid uses for locomotion through means of jet propulsion. This is done by sucking water into the mantle cavity and quickly expelling it out of the siphon in a fast, strong jet. The direction of the siphon can be changed in order to suit the direction of travel.Inside the mantle cavity, beyond the siphon, lies the visceral mass of the squid, which is covered in a thin skin. Under this are all the major internal organs of the squid.
http://taylorsinsight.blogspot.com/

g.) Body Plan: Like all cephalopods, squid are distinguished by having a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms and two tentacles arranged in pairs.
http://en.wikipedia.org/wiki/Squid#Digestive_system
Description of its unique habitat, diet and what distinguishes it as a mollusk, echinoderm, or arthropod.
-->Squids live in the ocean - a few, most notably the giant squid and the colossal squid live out in the colder open ocean. Many of the smaller species of squid rely on color changing patterns in order to communicate with each other and to attract prey as well. Squids are considered to be one of the most successful and highly complex of all invertebrates.
http://taylorsinsight.blogspot.com/

Starfish

a.) Digestive System: Starfish digestion is carried out in two stomachs: the cardiac stomach and the pyloric stomach. The cardiac stomach, which is a sack like stomach located at the center of the body may be everted—pushed out of the organism's body and used to engulf and digest food. Some species take advantage of the endurance of their water vascular systems to force open the shells of bivalve mollusks such as clams and mussels by injecting their stomachs into the shells. With the stomach inserted inside the shell, it digests the mollusk in place. The cardiac stomach is then brought back inside the body, and the partially digested food is moved to the pyloric stomach. Further digestion occurs in the intestine and waste is either excreted through the anus on the aboral side of the body, or if the anus is absent (as in brittle stars), waste is excreted through the mouth. http://en.wikipedia.org/wiki/Starfish#Digestion_and_excretion

b.) Circulatory System: Circulation occurs in three places: the perivisceral coelom (basically, the space inside the body but outside the various organs), the water vascular system (of which the tube feet are the most obvious part), and the hemal system (which actually looks something like a circulatory system). The hemal system is shown below. There are hemal channels forming rings around the central part of the body around the mouth (the oral hemal ring), closer to the upper surface (the aboral hemal ring), and a third ring around the digestive system (the gastric hemal ring). These are connected by the axial sinus. There are also radial hemal channels running down the rays next to the gonads (which are also located in the rays). A dorsal sac attached to the axial sinus pulsates, sort of like a very inefficient heart (inefficient because it lacks a one-way valve system). The hemal system seems mostly organized to distribute nutrients from the digestive tract.
http://www.vsf.cape.com/%7Ejdale/science/digest.htm

c.) Nervous System: Echinoderms have rather complex nervous systems, but lack a true centralized brain. All echinoderms have a nerve plexus (a network of interlacing nerves), which lies within as well as below the skin. The esophagus is also surrounded by a number of nerve rings, which send radial nerves that are often parallel with the branches of the water vascular system. The ring nerves and radial nerves coordinate the starfish's balance and directional systems. Although the echinoderms do not have many well-defined sensory inputs, they are sensitive to touch, light, temperature, orientation, and the status of water around them. The tube feet, spines, and pedicellariae found on starfish are sensitive to touch, while eyespots on the ends of the rays are light-sensitive. http://en.wikipedia.org/wiki/Starfish#Digestion_and_excretion

d.) Excretory System: None.

e.) Reproductive System: Starfish are capable of both sexual and asexual reproduction. Individual starfish are male or female. Fertilization takes place externally, both male and female releasing their gametes into the environment. Resulting fertilized embryos form part of the zooplankton. Some species of starfish also reproduce asexually by fragmentation, often with part of an arm becoming detached and eventually developing into an independent individual starfish. http://en.wikipedia.org/wiki/Starfish#Digestion_and_excretion

f.) Integumentary System: (structure ie skin, exoskeleton, shell, etc.)

g.) Body Plan: Most starfish have five arms, however some have more or fewer; in fact some starfish can have different numbers of arms even within one species. The mouth is located underneath the starfish on the oral or ventral surface, while the anus is located on the top of the animal. The spiny upper surface covering the species is called the aboral or dorsal surface. On the aboral surface there is a structure called the madreporite, a small white spot located slightly off-center on the central disc which acts as a water filter and supplies the starfish's water vascular system with water to move. http://en.wikipedia.org/wiki/Starfish#Digestion_and_excretion
Description of its unique habitat, diet and what distinguishes it as a mollusk, echinoderm, or arthropod.

Clam

http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-21-ClamAnatomy-L.jpg
a.) Digestive System: A clam has food brought in through a siphon system and then to its mouth. It then goes to a digstive gland and to its intestine. Wastes via the anus.

b.) Circulatory System: A clam has a heart, blood, and blood vessels.

c.) Nervous System: A clam has no formal nervous system, but has a series of ganglia that conduct impulses.

d.) Excretory System: A clam has an excretory system with an anus. It has an organ called the nephridium that gets rid of wastes.

e.) Reproductive System: A clam is either male or female and reproduces sexually with a large organ called a gonad.

f.) Integumentary System: A Mollusk has a soft, thick, fleshy body. It can be very small or as big as six feet across.

g.) Body Plan: A clam has a soft, thick, fleshy body. It can be very small or as big as six feet across.Description of its unique habitat, diet and what distinguishes it as a mollusk, echinoderm, or arthropod.

Crayfish- Virtual Dissection

a.) Digestive System: The digestive tract consists of the foregut, which includes an enlarged stomach, part of which is specialized for grinding; the midgut, which extends from the foregut; and the hindgut, which leads to the anus and functions in water and salt regulation (Miller and Harley, 1992; Snodgrass,1965). The digestive gland secretes digestive enzymes and aids in the absorption of the products of digestion (Pennak, 1989). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

b.) Circulatory System: The circlatory system of the crayfish is centred around a muscular heart with dorsal, anterior, and posterior arteries leading away from it . Branches of these vessels empty into the sinuses of the hemocoel (the large tissue spaces containing blood). The ventral sinus collects the blood, the blood travels through the gills, and then returns to the pericardial sinus surrounding ther heart (Miller and Hurley, 1992; Snodgrass, 1965). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

c.) Nervous System: The crayfish nervous system is composed of a ventral nerve cord fused with segmental ganglia, and the supresophageal and subesophageal ganglia (Miller and Harley, 1992). Giant neurons in the ventral nerve cord function in escape responses (Bliss, 1990). The supraesophageal and subesophageal ganglia control the head appendages in response to sesory input recieved from receptors (Miller and Harley, 1992). http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

d.) Excretory System: The excretory organs are also called the antennal glands because they are located at the base of the second antenna. They exrete the waste products of blood filtration; ammonia is the primary waste product (Miller and Harley, 1992). Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton (Snodgrass, 1965) http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

e.) Reproductive System: Crayfish have separate male and female sexes (dioecious) and the gonads are located in the dorsal portion of the thorax (Miller and Harley, 1992). Mating occurs just after the female has molted, usually in the spring. The male deposits sperm near the openings of the female gonoducts (at the base of the 3rd periopods) and uses the two modified pleopods to guide the sperm into the female sperm receptacle. http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

f.) Integumentary System: This crustacean has a hard exoskeleton that protects and supports the body. The crayfish has 8 jointed walking legs, a segmented body, 2 pairs of sensory antennae, and compound eyes. It has 2 large pincers or claws called chelipeds. If a crayfish loses a leg, the leg will regenerate (regrow). The head and thorax are fused, forming the cephalothorax. Using gills, a crayfish breathes oxygen that is dissolved in water. Juvenile crawfish are light tan, but adults are deep red. http://www.enchantedlearning.com/subjects/invertebrates/crustacean/Crayfishprintout.shtml

g.) Body Plan: The body of the crayfish is divided into two regions: the cephalothorax, which has sensory, feeding, and locomotor functions; and the abdomen, which has locomotor and visceral functions (Miller and Harley, 1992) http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CRAYFISH/CRAYFISH.HTM#Digestive

Description of its unique habitat, diet and what distinguishes it as a mollusk, echinoderm, or arthropod.--> Crayfish live in streams, rivers, swamps, ponds, and other freshwater habitats. Most crayfish are strictly aquatic but some live in semi-aquatic environments. The semi-aquatic crayfish burrow into the soil to get to water (so that they can breathe). Crayfish are omnivores; they eat plants, animals, and decaying organisms. They are nocturnal (most active at night) and eat fish, shrimp, water plants, worms, insects, snails, and plankton. Larval crayfish are very tiny; they eat plankton. Their color depends on diet. As a crayfish grows, it often molts (loses its old shell and grows a new one). It eats the old shell. http://www.enchantedlearning.com/subjects

Chapter 4 Critical Thinking

1.) During the day, algae carry out both photosynthesis and respiration, but at night, whent here is no light, they can only perform respiration. Small, isolate4d tide pools on rock shores are often inhabited by thick growths of seaweeds, which are algae. Would you expect the amount of oxygen in the water to differ between night and day? How?

--> Yes i would expext the aount of oxygen to decrease or lessen at night because without solar energy autotrophs do not produce oxygen.

Chapter 8 Critical Thinking
1.) Hagfishes and lampreys are the only living representatives of a very ancient group. Why do you suppose there are still some of these jawless fishes around?
--> Jawless fishes are know to be the most primitive fishes living today. I suppose they have exsited this long due to their feeding habits. They feed mostly on dead or dying fishes. This resource is simply impossible to run out off.
2.) A deep-water shark, new to science, is collected for the first time. The specimen is studied in detail, but its stomach is empty. How could you get a rough idea of its feeding habits? The specimen is a female, and its reproductive tract is found to contain 20 eggs. Can you tell the type of developement characteristic of this species?-->
In order to determine the feeding habits of this new specimen, you can study the jaws. Not all of the nearly 350 living species of sharks conform the same body plan, but the majority are known to contain rows of numerous sharp, often triangular teeth. This feature helps since sharks are known to be adapted for predatory feeding. Also to keep in mind, that there are sharks (whale sharks) that are filter feeders. This is could very well help explain an empty stomach. Because this specimen is yet to be unknown, it is hard to study the type of developement characteristic of the 20 eggs found. There are two different types of sharks that may very well affect the developement. One is oviparous and the other is viviparous. In an oviparous shark, the yolk is needed to provide energy for at least several months of development. Without this amount of time, the eggs won't be fully developed. And in a vivparous shark, nutrition is provided by direct contact with the reproductive tract of the female.
3.) Individuals of some species of bony fishes change sex, some to maintain more males than females, others more females than males. What are the advantages and disadvantages of each situation? Are there any advantages and disadvantages in having an equal number of males and females?
-->One advantage of maintaining more males than females is that there will be more chances of having a dominant male. Since a dominant male is needed to triger these changes (protandry and protogyny). A disadvantage of this situation will be that with less female, there will be less chances of reproduction. Whereas, this would be an advantage of having more females than males. And as for having an equal number of males and females, I think that there will be no advantages or disadvantages, since everything will turn out to be average.

Sea Floor Spreading

What is sea floor spreading?
-->Sea-floor spreading is the process in which the ocean floor is extended when two plates move apart. As the plates move apart, the rocks break and form a crack between the plates. Earthquakes occur along the plate boundary. Magma rises through the cracks and seeps out onto the ocean floor like a long, thin, undersea volcano. library.thinkquest.org/17457/platetectonics/4.php
What are some of the major land forms that are created from plate movement?
-->A long chain of mountains forms gradually on the ocean floor as magma piles up along the crack. This chain is called an oceanic ridge. library.thinkquest.org/17457/platetectonics/4.php
How were the Mariana Islands formed?
-->A theory known as plate tectonics presumes that the Asian continent and the North and South American continents are moving and that the Lithosphere (crust) of the continents are composed of different material. The edge of these plates are believed to be moving in such a manner that one moves under the other and the cataclysmic forces that result push material upward to form islands. www.cnmi-guide.com/history/formation
What evidence exists today that the plates are still moving and that the islands are ancient volcanoes?
-->Plate tectonics is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere. That facts that the fitting together of the coasts of the continents on the opposite sides of the Atlantic Ocean, the similarity of geologic formations and fossils found on the opposite sides, a geologically active mid-ocean ridge running along the central Atlantic between the opposite coasts, bottom sediments that get thicker the farther one travels from the ridge, and rocks on the sea floor on one side of the ridge show magnetic bands that are mirror images of rocks found on the opposite side of the ridge. en.wikipedia.org/wiki/Plate_tectonics#Plate_tectonic_theory
What is an atoll?
-->An atoll is an island of coral that encircles a lagoon partially or completely. Darwin (an English Naturalist) reasoned that a fringing coral reef surrounding a volcanic island in the tropical sea will grow upwards as the island subsides, becoming an "almost atoll" (barrier reef island). The fringing reef becomes a barrier reef for the reason that the outer part of the reef maintains itself near sea level through biotic growth, while the inner part of the reef falls behind, becoming a lagoon because conditions are less favorable for the corals and calcareous algae responsible for most reef growth. In time, subsidence carries the old volcano below the ocean surface, but the barrier reef remains. At this point, the island has become an atoll. http://en.wikipedia.org/wiki/Atoll




Why are atolls mainly found on the Pacific?
Atolls are the product of the growth of tropical marine organisms, so these islands are only found in warm tropical waters. Volcanic islands located beyond the warm water temperature requirements of reef building organisms become seamounts as they subside and are eroded away at the surface. An island that is located where the ocean water temperatures are just sufficiently warm for upward reef growth to keep pace with the rate of subsidence is said to be at the Darwin Point.http://en.wikipedia.org/wiki/Atoll