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.