squid

Circulatory 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.

Nervous system

The squid has the most complicated brain of all the invertebrates. The squids brain is estimated to have 300,000,000 neurons. These neurons are arranged in lobes and tracts that are more specialized than simple ganglia. An squid has a "good" memory and can also learn. The eye of the squid is very similar to that of vertebrates in that it has a cornea, lens, iris and retina. It can also focus and form images. However, the squid eye is different from that of vertebrates in that it focuses light by moving the lens closer and further away from the retina. The vertebrate eye focuses by changing the shape of the lens.squid can perceive shape, color intensity and texture. Another difference is that the eye of the squid has NO blind spot because the nerve cells leave from the outside of the eyeball. The squid also has a statocyst located next to the brain. The statocyst is used to detect changes in gravity and respond to acceleration.

Integumentary

The Male body was generated from scans of a live model. With optimized geometric resolution for detailed renderings, and a high level of anatomical accuracy representing an ideal physique. The Integumentary system currently comes with 2 models: Male skin w/ and w/o genitalia.

Excretory system

The kidneys remove wastes form the blood and maintain the body’s water balance, which are the primary oragans of the excretory system. Squid have an excretory organ to expel wastes fro the body .

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.

Body Plan

Squid has highly complex brains that rival the complexity of vertebrates. All of these species are highly active, agile predators. They possess a beak-like mouth that is used to rip apart captured prey items.

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 caaecum 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.

Habit

Squid inhabit naturally occurring dens on the ocean floor which are in crevices and under rocks for several weeks before they will find a new one. They are nocturnal, solitary creatures that hunt for several hours at night collecting food that is brought back to the den and devoured.

Diet

Adult diet includes mostly crustaceans, mollusks, and fish including small crabs, bivalves, snails and other squids). When eating shelled prey they may use arms to pull it apart, bite it with its beak or use the radula to actually drill through the shell. The mouth is able to secrete enzymes that soften the shell and toxins to paralyze prey and dissolve tissue

Distinguishes as molluscs

Squid have differentiated from their ancestral mollusks in such a way that the body plan has been condensed antero-posteriorly and extended dorso-ventrally. What before may have been the foot of the ancestor is now modified into a complex set of tentacles and highly developed sense organs, including advanced eyes similar to those of vertebrates.

The pictures are found in:

1. http://images.google.com/images
2. http://sps.k12.ar.us/massengale/squid_dissection.htm

clam

Respiratory System

Most species of clam have SEPARATE SEXES. There are both male and female clams.

The GONADS or reproductive organs (TESTES or OVARIES) are located dorsally near the pericardial cavity. Eggs and sperm are released into the mantle cavity. Fertilization in clams depends on the species: MARINE (ocean dwelling) clams – EXTERNAL FERTILIZATION Eggs and sperm are released into the mantle cavity and leave by excurrent siphon FRESHWATER clams- INTERNAL FERTILIZATION Sperm enter mantle cavity through the incurrent siphon; developing larva are discharged through the excurrent siphon and grow to adults.

Circulatory system

Clams have an OPEN circulatory system, meaning that the circulatory fluid (HEMOLYMPH) does not remain in vessels. It is collected from the gills, pumped thorough the heart, and released directly into spaces in the tissues. Open circulation is NOT AS EFFICIENT as a closed system because nutrients and oxygen are not pumped directly to organs. In addition, high oxygen and low oxygen blood can mix allowing fewer nutrients and oxygen to reach the cells.

Nervous system

Clams have NO CEPHALIZATION. There is NO distinct head area. Instead of a pair of cerebral ganglia in the head connected to one ventral nerve cord like an earthworm, a clam’s nervous system consists o 3 PAIRS of GANGLIA throughout the body
connected by TWO PAIRS of long NERVE CORDS. Nerve cells in the ganglia control the muscles involved in locomotion and feeding, and process sensory info about light, touch, and chemicals (food) in the water. Clams follow the same body plan seen in earthworms and other invertebrates with a DORSAL HEART and a VENTRAL NERVE CORD.

Excretory system

The excretory organ in clams is the KIDNEY. This organ collects nitrogen waste produced by body cells from the break down of proteins and excretes it into the mantle cavity where it is removed with water exiting through the excurrent siphon.
The kidney also maintains the balance of water and ions in the body (OSMOREGULATION).

body plan

The first dissection shows a clam which has been opened by cutting the large adductor muscles, which attach to both valves and thus function to close the shell. On the inside of the shell that has been separated, note the places where the adductor muscles attach. A thin sheet of tissue, the mantle (most of which has been cut away) covers the animal's body and secretes the shell. On the separated valve, note the line along which the mantle was attached. The mouth is hidden under a pair of labial palps above the adductor muscle to the left; therefore the anterior end of the animal is to the left. On the ventral (bottom) side is the large muscular foot, which attaches to the shell via smaller retractor muscles. The foot contains portions of the digestive and reproductive organs, and also serves as an appendage for burrowing into the mud. The region dorsal to the foot is called the visceral mass.

Digestive System

The second dissection on display shows a clam that has been cut along the midline of the body. The food particles that are filtered from the water passing through the ctenidia are carried anteriorly by water currents and guided to the mouth by the labial palps. A short esophagus leads to the irregularly-shaped stomach, which is embedded in the greenish digestive gland (1iver). From the stomach, the intestine extends through the pericardial cavity to the rectum, which is located dorsal to the excurrent siphon. The gonads from a yellowish mass among the loops of the intestine. Their ducts, which will not be seen here, open into the suprabranchial chamber.

Integumentary system

A hard outer shell and a soft body. It uses a muscular foot for movement. The skin is the largest organ in the body: 12-15% of body weight, with a surface area of 1-2 meters. Skin is continuous with, but structurally distinct from mucous membranes that line the mouth, anus, urethra, anv vagina. Two distinct layers occur in the skin: the dermis, and epidermis. The basic cell type of the epidermis is the keratinocyte, which contain keratin, a fibrous protein. Basal cells are the innermost layer of the epidermis. melanocyte produce the pigment melanin, and are also in the inner layer of the epidermis. The dermis is a connective tissue layer under the epidermis, and contains nerve endings, sensory receptors, capiliaries, and elastic fibers.

Habit, diet, life cycle distinguishes and reproduction:

• The life cycle of the hard clam includes a pelagic larval phase and relatively sedentary benthic juvenile and adult phases.
• Hard clams begin their adult lives as males, often become females with greater maturity, and require individuals of both sexes for reproduction.
• Clams develop functional male gonads during the first or second year of life.
• Spawning cycles are affected mainly by water temperature and the availability of food, and thus vary according to latitude. Spawning often occurs in "pulses" and may continue for months, but usually there are one or more distinct spawning peaks.
• In the Chesapeake Bay region, spawning usually commences when temperatures rise above 20-23 degrees C (68-73 degrees Fahrenheit.
• Female fecundity is high, and individuals can release 16 million to 24 million eggs per spawn, although laboratory studies often have recorded values of only 1-3 million eggs, and only a few will reach maturity.
• Individuals may release as many as 60 million eggs during one season.
• Eggs are 70 to 73 microns in diameter and are surrounded by a gelatinous membrane. Eggs and sperm of adults are expelled in the water current and fertilization occurs externally in the water column.
• In the Bay area, the most significant growth occurs in spring and fall, when abundant food and optimum water temperatures coincide. Growth decreases in summer and stops altogether in winter. Growth rate also decreases with age, and when this happens, clams become thicker, rather than increasing in shell length.
• Most larval stages of the hard clam swim toward light (or opposite force of gravity), so most are concentrated in the surface waters and are dispersed by wind, waves, and current.
• The pediveliger stage is the final larval stage before settlement and metamorphosis to juveniles. At this stage the organism has a foot that extends from its shell.
• Once the hard clam settles to Bay bottom, it uses its foot to dig into the mud, and secretes a calcium carbonate shell that increases in size as the clam’s internal organs grow.
• The most growth takes place in temperatures between 10 C (50 F) and 25 C (77 F). A cross-section of a hard clam’s shell usually reveals a clam’s age. Hard clams may live for more than 30 years, and occasionally reach 50 years.
• Clam is distinguished as mollusk. Because it has an outer shell and has a soft body. It has a muscular foot that it uses for movement.
• Calm eat small plants and animas called plankton.

The pictures are found in:

1. http://images.google.com/images
2. http://sps.k12.ar.us/massengale/crayfish_dissection.htm

Excretory: it is 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 Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton

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 .

Nervous System: The crayfish nervous system is composed of a ventral nerve cord fused with segmental ganglia, and the supresophageal and subesophageal ganglia. Giant neurons in the ventral nerve cord function in escape responses . The supraesophageal and subesophageal ganglia control the head appendages in response to sesory input recieved from receptors .

Reproductive system: Crayfish have separate male and female sexes (dioecious) and the gonads are located in the dorsal portion of the thorax. 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.

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 .The digestive gland secretes digestive enzymes and aids in the absorption of the products of digestion

Integumentary system: crayfish has hard exoskeleton that covers its body. its body is divided into two main parts, the cephalothorax and the abdomen. The cephalothorax consists of the cephalic (or head) region and the thoracic region. The part of the exoskeleton that covers the cephalothorax is called the carapace. The abdomen is located behind the cephalothorax and consists of six clearly divided segments. The cephalothorax consists of 13 segments. Each segment of both the cephalothorax and the abdomen contains a pair of appendages. The head (or cephalic) region has five pairs of appendages. The antennules are organs of balance, touch, and taste. Long antennae are organs for touch, taste, and smell. The mandibles, or jaws, crush food by moving from side to side. Two pairs of maxillae hold solid food, tear it, and pass it to the mouth. The second pair of maxillae also helps to draw water over the gills. Of the eight pairs of appendages on the cephalothorax, the first three are maxillipeds, which hold food during eating. The chelipeds are the large claws that the crayfish uses for defense and to capture prey. Each of the four remaining segments contains a pair of walking legs. In the abdomen, the first five segments each have a pair of swimmerets, which create water currents and function in reproduction. The sixth segment contains a modified pair of uropods. In the middle of the uropods is a structure called the telson, which bears the anus. The uropod and telson together make up the tail fan. The crayfish moves backward by forcing water forward with its tail fan.

Body plan: A crayfish has a lot of body parts. The most important parts of a crayfishes body are the carapace, tail, legs, heart, claws, brain, egg pores, long antenna, short antenna, stomach, digestive gland, bladder,intestines, modified swimmerets, and swimmerets.

Habitat and diet: A crayfish`s habitat is a lake near shallow water under rocks. The pond or lake is were you would probably find one. Crayfish eat many things. In there natural habitat they will eat fish, earth worms, tadpoles, snails, plants, and small fish. To distinguishes crayfish, you have to look at its body just as legs, tail, out surface of the body, claws and its activities.

The pictures are find in:

1. http://images.google.com/images

2.http://sps.k12.ar.us/massengale/crayfish_dissection.htm

Amphipods

Scientific classification:

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacean

Class: Malacostraca

Order: Amphipoda

Species: Mutualistic

Family: glacial reliscts

Genus: phronima
Habitat: living in living on the ocean bottom in mud or sand association with jellyfish and salps.

Food source: bacteria on the surface of particles, or scavengers on dead animals or plants
Description of life cycle (egg to death): The reproductive period started in October, and hatchlings were released from November until July. Four cohorts were present in November. Some one-year-old females appeared to reproduce more than once. Ontogenetic niche segregation occurred from June to September, when juveniles were found in shallow water and adults were found in deep water where temperatures were below 10°C.
How does it move (if it moves): Amphipods move depends on the arrangement of their legs. Most walk upright using most of the thoracic legs but this is very slow. Swimming using the three pairs of pleopods is much faster. The speciality of amphipods is the tail-flip, a rapid escape response where the abdomen flicks the animal away after the uropods are dug into the ground.

Unique characteristics: long and skinny and flattened from side to side, but more accurately they are defined by the presence of three pairs of uropods (tail-limbs) and usually by having the first two pairs of legs modified to help with grasping food. There is no carapace; seven thoracic and six abdominal segments are visible. The head carries two pairs of antennae, the eyes which are not on stalks, and the mouthparts. Amphipods have seven pairs of walking legs of which the first four reach forward, and the fifth to seventh reach backwards. The abdomen is divided into two parts, three segments with brush-like limbs and three with short immobile rod-like uropods.
Role in the ecosystem: some of them live their lives attached to marine mammals. These whale-lice are ectoparasites which cling firmly to, and feed on, the skin of whales. Unlike other amphipods, whale-lice cannot swim so once the juveniles leave the brood chamber of the female they attach themselves close by. In addition, the amphipods were infested by several parasites, including larvae of Cystidicola sp., a swimbladder nematode that infects fish.

Organism - Sea Star

Sea stars also called starfish, which are spiny, hard-skinned animals that live on the rocky sea floor. These invertebrates are NOT fish but they are echinoderms. Sea stars move very slowly along the sea bed, using hundreds of tiny tube feet. There are over 2,000 different species of sea stars worldwide.

Reproduction: Most species of starfish expel enormous numbers of eggs and sperm into the ocean; fertilization is external. After fertilization, the tiny, transparent, bilaterally-symmetrical larvae (baby sea stars) travel many miles as they are swept along by ocean currents for about two months. As they develop, the tiny larvae swim in the sea, eat phytoplankton, and are a component of zooplankton.

Diet: Sea stars are carnivores (meat-eaters). They eat clans, oysters, coral, fish, and other animals. They push their stomach out through their mouth (located on the underside of the sea star) and digest the prey.

Anatomy: Most sea stars have five arms (or a multiple of five) that radiate from a central disk. Sea stars do not have a brain; they have a simple ring of nerve cells that moves information around the body. Eyespots (primitive light sensors) are at the tip of each arm. If a sea star's arm is cut off, it will regenerate (regrow).

Classification: Kingdom Animalia (animals), Phylum Echinodermata echinoderms, Class Asteroidea (sea stars), about 2,000 species.

Role in the ecosystem: Sea stars are one of the best known invertebrates. They are also ecologically important because they can be important predators of other invertebrates like clams, barnacles and other attached marine life. They can be brightly colored and, in many species, show considerable variability in color within one species.

Unique characteristics: with a flattened, star-shaped body, have 5 arms or multiples of 5 arms , Spines or reduced spines on outer surface , walk using many tube feet that have suckers on their ends, a mouth on bottom (oral) surface and anus on the upper (aboral) surface of your body and eat both plants and animals (an omnivore).

chapter 6-Critical thinking

Only very few flowering plants have invaded the ocean,but those that have are very successful.What are some posible reasons for the small number of marine flowring plants? How do those that have taken the step manage to thrive in some environments?

- flowering plants live submerged by seawater,rearely exposed at low tide. Salt-marsh grasses and mangroves inhabit estuaries and shores protected from wave action. Their roots are usually covered by water at hight tide. They adapted to colonize coastal areas exposed to salt-laden winds and occasional sea spray,though they do not tolerate immersion in seawater. They can live on the sand dunes or living along the edges of salt marshes.

chapter 5 -Critical thinking

An autotrophic protist, such as a diatom or a dinoflagellate, can evolve into a heterotrophic protist (and therefore a protozoan) simply by losing its chloroplasts.Under what conditions might this take place?

-It is when photosynthesis takes place on folded membranes within the bacterial cell rather than in chloroplasts as in algae and plants.