Mechanisms of Speciation

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IMG_5534Mechanisms of Speciation

Mechanisms of Speciation

For this assignment I chose the iguana and the two specific species are the banded iguana and the crested iguana.

These 2 iguanas are closely related and are the most geographically isolated iguanas in the world. They are believed to have evolved from green iguanas that rafted on debris across the Pacific Ocean from South America.

Banded Iguana

The Banded iguana (Brachylophus fasciatus) is an arboreal species of lizard, which means that is lives among trees. This species generally lives in the southeastern Fijian islands. These islands include: Wakaya, Moturiki, Beqa, Vatulele, Ono, Dravuni, Taveuni, Nggamea, Vanua,Balavu, Avea, Vatu Vara, Lakeba, Aiwa, Oneata, Vanua Levu, Totoya, Kabara, andFulaga

Physical Adaptations:

• Males have pale, bluish-green bands covering their green bodies. Females are usually entirely green
• The banded iguana’s skin color changes in response to light, temperature, and its mood
• Tail has alternate bands of white and green
• Eyes are reddish-orange. Short spiny crest on back
• Snout to tail length 60cm

Habitat/Biome:

• tropical forests, lowlands, and swamps of the Fiji islands
• Fiji, Tonga, Vanuatu

Evolution

• Has a long tail that helps it balance
• Thin and small so it is able to jump from tree to tree, it rarely goes on the ground
• Feeds on leaves, fruit, and flowers of trees and shrubs, particularly hibiscus flowers of the Vau tree found on the islands listed above.
• Developed the ability to eat insects

Crested Iguanas
The Fiji crested iguana (Brachylophus vitiensis) is from the northwestern islands of Fiji, Yadua Taba, Monuriki, and Macuata
Physical Adaptations

• Large and stocky
• It has the ability to change colour, depending on mood or situation
• Bright green colour with white bands across the body
• 75cm from the nose to the tip of the tail

Habitat

• Dry or coastal forests
• Can also be found on rocky cliffs

Evolution

• Has a spiky spine to fend of predators
• Does not need to hunt insects so it is larger, shorter and stockier
• The male crested iguana is able to change colour very rapidly from green to black when it is aroused. The darker colour makes the white bands stand out.
• found perching in flowering trees so has evolved into having strong legs and sharp claws which is good for climbing
• herbivore, feeds on trees and shrubs. All male iguanas are very visual and each species has evolved into having there own tactics of scaring off other males. Both species of iguanas deepens and bobs their heads and intimidate intruders by lunging at them with open mouths.

The banded iguana and the crested iguana have developed these differences over time because of speciation. The main mechanism of speciation is geographic isolation or allopatric speciation.

In this mode of speciation, something extrinsic (originating from the outside; external) to the organisms prevents two or more groups from mating with each other regularly. This causes them to speciate.

Populations of the same species in different geographic locations would become genetically different. A lot of the times the species become different in appearance and slightly different genetically. Genetic differences may happen because of reduced gene flow. Gene flow is the movement of genes between populations. This may happen through the migration of organisms

Due to habitat destruction and, more significantly, the introduction of mongooses and house cats to the islands, populations of these iguanas have been declining over the past century. Both species of Fijian iguanas are considered to be endangered and have full protection under both Fiji and international laws.

Plant Study

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IMG_4685Blog 10: Plant Study
For my plant study I chose to focus on the vascular plant commonly known as lantana, the official scientific name is lantana camara. The family that the Lantana belongs to is the Verbenaceace (Verbena Family). The kingdom is Plantae, a multi-cellular organism that produces food through photosynthesis. The order is Lamiales which is an order of dicotyledonous flowering plants. Dicotyledonous otherwise known as dicot, is a plant whose seed typically has two embryonic leaves or cotyledons. The genus is Lantana and the species is Lantana Camara. The phylum is called Magnoliophyta which is a comprising flowering plant that produce seeds enclosed in an ovary; in some systems considered a class (Angiospermae) and in others (Magnoliophyta or Anthophyta)

The Lantana camara is a low shrub which can grow to 2 – 4 meters in height. The leaves are bright green, rough, finely hairy, with serrate margins and give out an odour when crushed. Lantana is able to climb to 15 m with the support of other vegetation. Flower heads contain 20 – 40 flowers, usually 2.5 cm across; the colour can vary from white, cream or yellow to orange pink, purple and red. Flowering occurs between August and March, or all year round if there is enough moisture and light. Pollinators include lepidopteran species and thrips.

Mature plants produce up to 12,000 seeds annually. Seed germination occurs when sufficient moisture is present; germination is reduced by low light conditions. The root system is very strong with a main taproot and many fibrous roots.

I found out that the Lantana Camara can grow all around the world, which reflects its ability to adapt in different ecological environments. It can grow on a variety of soil types, it generally grows best in open, un-shaded conditions such as wastelands, the edges of rain forests, on beachfronts, in agricultural areas, grasslands, riparian zones, scrub/shrub lands, urban areas, wetlands and forests recovering from fire or logging. Roadsides, railway tracks and canal banks are favored by the Lantana. It doesn’t grow at temperatures below 5 C. The plant is found at altitudes from sea level to 2,000 m and thrives very well with rainfall ranging from 750 to 5000 mm per annum. Where natural forests have been disturbed from logging, which creates gaps, the Lantana encroaches in the gaps. Logging damages the environment and allows lantana to spread and become thicker. It cannot survive under dense canopies with tall trees. The plant is exposed to frosts and low temperatures, saline (salty) soils, boggy or hydromorphic soils, low rainfall and tropical hurricanes.

Water Transport

There are complex vascular systems that move nutrients and water throughout the plant body through “tubes” of conductive cells. The vascular tissues of these plants are called xylem and phloem. The xylem of vascular plants consists of dead cells placed end to end that form tunnels through which water and minerals move upward from the roots to the rest of the plant. Phloem, which is made up of living cells, carries the products of photosynthesis (organic nutrients) from the leaves to the other parts. The vascular system is continuous throughout the whole plant, even though the xylem and phloem are often arranged differently in the root than they are in the shoot.

The main way water is carried upward through the xylem is called TATC (Transpiration-Adhesion-Tension-Cohesion.)

Water transport also occurs at the cellular level, individual cells absorb and release water, and pass it along to neighboring cells.

Water enters and leaves cells through osmosis, the diffusion of water across a membrane. In plants, water always moves from an area of higher water potential to an area of lower water potential.

Most of the water that a plant takes in enters through the root hairs. Overall, water is transported in the plant by individual cells and the conductive tissues. Water from the soil enters the root hairs and into the xylem through either the apoplast or symplast pathway. It is carried upward through the xylem by transpiration, and then passed into the leaves along another water potential gradient. Water potential gradient is when water flows down a gradient from higher potential to lower potential. Higher potential is generally in the soil/roots and lower potential is at the leaves/atmosphere. In the leaf, some water is lost through evaporation from the stomata and the remaining fluid moves along a water potential gradient from the xylem into the phloem, where it is distributed along with the organic nutrients produced by photosynthesis throughout the plant.

Reproductive Mechanisms

Flowers, the reproductive structures of angiosperms, (a plant that has flowers and produces seeds) are adaptations designed to attract insects. For this reason, flowers are most often colorful and showy.
Plants that rely on wind (instead of insects) for pollen dispersal have flowers that are more likely to be small. The flower is made up of four leaves, the calyx, corolla, androecium, and gynoecium. Each of these contains one of the flower organs, the sepals, petals, stamens, or pistils. Sepals and petals are not directly involved in reproduction, while the stamens and pistils are the male and female reproductive organs. Also, each flower has an ovary which is formed from modified leaves called carpels. This ovary, which is exclusive to angiosperms, encloses the ovules and turns into a fruit after fertilization.

Calyx

The calyx is made up of sepals, green leaf-like structures that enclose the unopened bud. They serve a protective role for the flower before it opens, and afterward extend from the base of the flower.

Corolla

The corolla is made up of the petals of the flower, which are usually brightly colored in order to attract insects. Together, the corolla and calyx make up the perianth, the nonreproductive portion of the flower.

Androecium

The androecium is composed of the male reproductive organs, the stamens. Each stamen consists of a long, slender filament with a pollen-producing anther. Microspores develop, into pollen grains, which carry sperm cells to the female reproductive organs.

Gynoecium

The gynoecium, composed of a pistil or pistils, lies in the very middle of the flower. The top of the pistil, where pollen grains land, is called the stigma and the shaft leading down into the ovary is called the style. The ovary, containing ovules and egg cells, makes up the very bottom of the pistil.

The Lantana camara has several medicinal properties and it is used in folk medicine with antipyretic, antimicrobial and antimutagenic properties.

Ecosystem Restoration

Ecosystem Restoration

Definition: http://www.reefresilience.org/Toolkit_Coral/CCR_CoralRestoration.html)
Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed.
Biodiversity is comprised of the millions of different species that live on Earth, as well as the genetic differences within species. It also refers to the different ecosystems in which species form communities.
We need biodiversity to satisfy basic needs like food, drinking water, fuel, shelter, and medicine. Much of the world’s population still uses plants and animals as a primary source of medicine. Ecosystems provide services such as pollination, seed dispersal, climate regulation, water purification, nutrient cycling, and control of agricultural pests. Other reasons that biodiversity is important include:

• Ecosystem services, such as
o Protection of water resources
o Soils formation and protection
o Nutrient storage and recycling
o Pollution breakdown and absorption
o Contribution to climate stability
o Maintenance of ecosystems
o Recovery from unpredictable events
• Social benefits, such as
o Research, education and monitoring
o Recreation and tourism
o Cultural values

Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play.

The ecosystem restoration project that I chose to focus on is coral reef planting. Coral Reefs are suffering from natural and anthropogenic threats. Anthropogenic means human influence or human impact. Many anthropogenic influences are resulting in the degradation and destruction of coral reefs causing loss of biodiversity and essential food supplies. Combined with threats from nature in the form of storms, typhoons and diseases, coral reefs are struggling to survive.
Impacts such as ship groundings, coral mining and blast fishing can cause major physical damage to coral reefs. Physical restoration focuses on repairing the reef, major physical restoration is generally an expensive engineering project.
There are two main types of physical restoration:
1. Repair of damaged reefs — In cases where impacts have cracked coral boulders, overturned massive corals, moved and separated coral colonies and other organisms, restoration in the short term can help with recovery. This may involve applying cement or epoxy to large cracks in the reef framework, or fixing and reattaching corals, sponges and other reef organisms.
2. Artificial reef creation — Artificial reefs are built out of hard, durable structures such as rock, concrete, and steel, usually in the form of surplus or scrap materials (e.g. vessels, dredge rock, and military vehicles, etc.)
I think what these organizations are doing is hugely important and the restoration project that we visited was very impressive. They are not only educating tourists but locals as well. The key is to inform the younger generation so that this project continues. Now they need to expand the project but not only in Fiji, in other countries as well. There needs to be more awareness of the destruction of coral reefs because it is one of the most important ecosystems.
Attached is a video about coral reef planting in Fiji.

Antibiotic Resistance

Antibiotic Resistance
Antibiotics, also known as antimicrobial drugs, are drugs that fight infections caused by bacteria. Antibiotics are powerful drugs, but they are not the cure for every ailment. They are not effective against viral infections like the common cold.

Almost all-important bacterial infections are becoming resistant to antibiotics. Antibiotic resistance has been called one of the world’s most pressing public health problems. Smart use of antibiotics is the key to controlling the spread of resistance.

Antibiotic resistance occurs when an antibiotic has lost its ability to effectively control or kill bacterial growth. The bacteria become “resistant” and continue to multiply.
They become resistant because when an antibiotic is used, bacteria that can resist that antibiotic have a greater chance of survival than those that are “susceptible.” Susceptible means easily influenced or affected.
It is possible for bacteria to produce and use antibiotics against other bacteria, which leads to resistance. However, the biggest cause for antibiotic resistance is the overuse and abuse of antibiotics. Antibiotics can be purchased without a doctor’s prescription. Patients sometimes take antibiotics unnecessarily, to treat viral illnesses like the common cold.

Bacteria become resistant because some bacteria are naturally resistant to certain types of antibiotics. However, bacteria may also become resistant in two ways: 1) by a genetic mutation or 2) by acquiring resistance from another bacterium.

Changes in the bacteria’s genetic material occur in about one in one million to one in ten million cells. Different genetic mutations produce different types of resistance. Some mutations enable the bacteria to produce enzymes that inactivate antibiotics, while other mutations eliminate the target of the cell that the antibiotic attacks.

Bacteria can get antibiotic resistance genes from other bacteria. By a mating process called “conjugation,” bacteria can transfer genetic material, including genes encoding resistance to antibiotics from one bacteria to another.
Any bacteria that acquire resistance genes, either by mutation or genetic exchange with other bacteria, have the ability to resist one or more antibiotics. Due to the fact that bacteria can collect multiple resistance traits over time, they can become resistant to many different families of antibiotics.

Antibiotics are important but they are designed for bacterial infections and should not be used for colds, cough, or the flu. Here are some tips from http://www.rxlist.com/script/main/art.asp?articlekey=115605&page=4 on how to prevent antibiotic resistance.

1. Talk with your healthcare provider about antibiotic resistance:
- Ask whether an antibiotic is likely to be beneficial for your illness
- Ask what else you can do to feel better sooner
2. Do not take an antibiotic for a viral infection like a cold or the flu.
3. Do not save some of your antibiotic for the next time you get sick. Discard any leftover medication once you have completed your prescribed course of treatment.
4. Take an antibiotic exactly as the healthcare provider tells you. Do not skip doses. Complete the prescribed course of treatment even if you are feeling better. If treatment stops too soon, some bacteria may survive and re-infect.
5. Do not take antibiotics prescribed for someone else. The antibiotic may not be appropriate for your illness. Taking the wrong medicine may delay correct treatment and allow bacteria to multiply.
6. If your healthcare provider determines that you do not have a bacterial infection, ask about ways to help relieve your symptoms. Do not pressure your provider to prescribe an antibiotic.

An example of antibiotic resistance is in Fiji. There is a disease called Shigellosis, deaths in Fiji are rare but antibiotic resistance is causing many issues with managing the problem of Shigellosis.

Lactase Evolution (natural selection

Blog 3: Lactase Evolution (natural selection)

Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products.
Symptoms of lactose intolerance include:
• a bloated stomach
• flatulence (wind)
• diarrhea

Intolerance is not the same as a food allergy. If you’re allergic to something, even a tiny particle can be enough to trigger a reaction, while most people with lactose intolerance can still consume small amounts of lactose without horrible effects.
The amount of lactose a person can consume can change, from person to person.
The body digests lactose by using an enzyme called lactase to break down lactose into two simpler sugars called glucose and galactose, which can then be easily absorbed into the bloodstream. Enzymes are proteins that cause chemical reactions to occur.

In cases of lactose intolerance, the body does not produce enough of the lactase enzyme so lactose stays in the digestive system, where it is fermented by bacteria. It’s this fermentation process that causes the symptoms associated with lactose intolerance.

Primarily people, whose ancestors came from places where dairy herds could be raised safely and economically, such as in Europe or in India, have developed the ability to digest milk. India historically had cows and they were considered sacred. Fiji, on the other hand, did not have cows historically and many Fijians are lactose intolerant. Another way to explain why Fijians are lactose intolerant is Darwin’s process of natural selection.

Natural selection has three components.
1. Variation. Organisms (within populations) have individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring.
2. Inheritance. Some traits are consistently passed on from parent to offspring.
3. Differential survival and reproduction. Individuals possessing traits well suited for the struggle for local resources contribute more offspring to the next generation.

From one generation to the next, the struggle for resources (what Darwin called the “struggle for existence”) will favor individuals with some variations over others. Some populations become lactose intolerant because if there aren’t cows early on in the countries history, they will not be able to accustom to digesting lactose. Therefore they will not pass down the ability to digest lactose to offspring. In this case Indians have the ability to digest milk because of two out of the three natural selection components, inheritance and survival and reproduction. Indians had access to cows early on and lactose tolerance was passed down from parent to offspring for many years. For differential survival and reproduction, Indians were well suited to compete for survival off of local resources and in this case, cows.
When it comes to the Indo-Fijian population there is less lactose intolerance. The Indians who moved to Fiji brought the genetic ability to digest lactose with them and it continues to be passed down. Native Fijians do not have cows in their country so they were never able to develop this genetic ability.

Koroniva Research Station

IMG_5131Blog 5: Korniva Research Station
Today we learned about insects, more specifically invasive insects, as well as food production, agriculture and we went into the chemistry lab. The information that I was the most interesting in was food production as well as the narcotic trade in Fiji. I have chosen to do my summative assignment on those topics so I have decided to write about the Coconut Stick insect.
The coconut industry is very important to Fiji, supporting the livelihoods of millions of people throughout the Asia-Pacific region. Coconut Stick insects, let’s call them (CSI) haha, are across all islands of Fiji, they feed at night and are inactive during the day. With their stick-like-appearance and leaf colouring CSI camouflage. To Fijians, the Coconut Stick insect is referred to as “mimimata.” Both the nymph and adult insects feed on the leaves, leaving only the midrib. They defoliate the whole plant, which leads to the death of the plant.
There are a couple options that Fijians are using to manage the CSI population. The first option is the releasing of Black wasps into infected fields to kill the eggs. The second option is intercropping with non-host plants like Taro and Cocoa. The final option is cattle grazing in coconut plantations. This not only kills the eggs but the cattle keep the weeds in check. The insect pest management is working to rid Fiji of these insects so that the coconut industry can continue to thrive.

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SHARK WATERR!!

Shark Water Questions
1. Predators:
In the documentary it is said, “predators control the ecosystem”. Predators greatly affect the food web, keeping in check the negative impacts other animals have on natural systems if too abundant.
2. Long Line Fishing:
A heavy fishing line usually several miles long that has a series of baited hooks. It Is an illegal form of fishing used to catch sharks, fish and sometimes turtles. Sharks entangle themselves in the line and suffocate. In Shark Water 60 miles of sharks were dying. As it said in the film long line fishing removes the controlling agent and causes an appeal.
3. Sharks in the Ecosystem:
Sharks are crucial to ecosystem in the ocean. They are said to be the lions and tigers of the sea. They are the perfect predators that hold the underwater balance. Sharks control the population in the ocean. For example sharks control the fish population, without that the fish would eat the plankton. Plankton converts carbon dioxide into oxygen.
4. Chromosomes:
Sharks have 24 chromosomes and humans have 46. Chromosomes are in a the cell nucleus, it is a thread-like structure made mostly of DNA.
5. Different Sharks:
Hammerhead Sharks: Sphyrna
Silvertip Shark: Carcharhinus albimarginatus
6. Scientific Names
The scientific name for a species is either in Latin or Greek, the language used by the first taxonomists. Over time, this has remained the case, and the universal way of describing organisms to avoid mis-understandings which can arise when using the common name of a species.
7. Characteristics of a Shark:
Sharks are fish that have been around since long before the dinosaurs existed. They live in waters all over the world, in every ocean. Unlike bony fish, sharks have no bones; their skeleton is made of cartilage, which is a tough, fibrous substance, not nearly as hard as bone. There are many different species of sharks that range in size. There are about 368 different species of sharks, which are divided into 30 families.
The largest sharks are decreasing in numbers around the world because of being killed by humans.
9. Sharks Systems:

“3. Circulatory and Respiratory System.” Sharks. N.p., n.d. Web. June 2013.

Circulatory System
A shark’s heart is a two-chambered S-shaped tube, small in proportion to body size located in the head region. Has an atrium and ventricle. The blood is pumped by the heart through the afferent branchial arteries to capillaries in the gills, where the blood is oxygenated). The blood then flows through efferent branchial arteries, through the tissues of the body, and back to the heart in veins. Sharks have low blood pressures; the walls of the pericardium are rigid, creating suction within the pericardium to maintain the flow of blood. To circulate blood throughout their bodies, many sharks must swim continuously. Most sharks are cold blooded which requires them to constantly move and use external heat sources to maintain body temperature.

Respiratory System
Sharks can respire by pumping water over their gills by opening and closing their mouths. From the mouth, water enters the gill chambers and exits through the gill slits. Blood in the gill filaments absorbs oxygen from the incoming water. Gill rakers, which are cartilaginous projections on the gill support structure, protect the delicate gill filaments from particles in the water that might damage them. Because sharks have low blood pressure, most must swim continuously because muscular contractions are needed to circulate the blood. Oxygen is absorbed by gills. Sharks also absorb oxygen from water rather than the air like humans do.

Digestive System
Most sharks swallow their food whole or bite it into relatively large pieces. Sharks have U-shaped stomachs that use very strong acids and enzymes to dissolve most of what is eaten. The stomach produces an easily absorbed, soupy mush. Only this liquid mush enters the intestines because the pyloric valve (the valve between the stomach and the intestines) is small. Indigestible things, (like very large bones and non-nutritive items) are vomited.

Absorption of nutrients takes place in the intestines. Although the intestines are short, they have a large surface area due to infolding of the inner surface of the intestines. Some shark intestines are arranged in folds, some are in a spiral pattern, like a spiral staircase enclosed within a cylinder.
10. Seals:
Sharks have a tough time catching seals. They have mobile back bones which makes them agile. A healthy seal doesnot make noise or produce bubbles. To catch them sharks have to ambush the seals by swimming below out of visible range, looking for their silhouette. It is interesting that not more humans have been attacked considering how similar they look to seals.

11. Flesh Eating Disease:
Flesh-eating disease is more properly called necrotizing fasciitis, it is a rare condition in which bacteria destroy tissues underlying the skin. This tissue death, called necrosis or gangrene, and it spreads rapidly. The disease infects the body through any wound. This disease can be fatal in as little as 12 to 24 hours.

Prokaryotes of Fiji

The prokaryote that I chose for this blog was Cyanobacteria.Cyanobacteria also known as blue-green bacteria, blue-green algae, and Cyanophyta, are a phylum of bacteria that gets its energy through photosynthesis. It is a primitive life form (being little evolved) that is closely related to bacteria. Cyanobacteria are aquatic and photosynthesize like algae. They live in water and can produce their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. Cyanobacteria have a characteristic pigment which gives the group their blue-green coloration. When cyanobacteria blooms begin to die and disintegrate, this pigment may colour the water a distinctive bluish color. Cyanobacteria are found throughout the world in terrestrial, freshwater and marine habitats, but blooms typically occur in freshwater. Cyanobacteria can be found in almost every terrestrial and aquatic habitat—oceans, fresh water, damp soil, temporarily moistened rocks in deserts, bare rock and soil, and even antarctic rocks. Cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth.

While there is an almost endless variety of cells in the world, there are two main categories used to classify them.
1) Prokaryotes
-The smallest living cells.
-are almost all unicellular
-Relatively simple internal structures.
-All bacteria are prokaryotes.
-“pro” means before, and “karyon” means nucleus, so prokaryotes do not contain a nucleus.
-Their DNA is concentrated in an area called a nucleoid.
-They are the most abundant cells on earth.
-They can survive in diverse and extreme habitats.
-They lack most organelles.
2) Eukaryotes
-“Eu” mean true, and they do contain a nucleus. The nucleus in an enclosed region that separates the DNA from the rest of the cell contents.
-Eukaryotes contain specialized structures called organelles to perform specific functions within the cell.

Comparative Anatomy

Blogs: ANATOMY
Comparison Table Between a Sharks and a Human’s Digestive System

Sharks and Humans have many shared aspects of their anatomies as well as aspects that pertain to only their species. Both sharks and humans have a brain, heart, spleen, kidney (2 for sharks and 1 for humans), a pancreas, liver, stomach, gall bladder and Esophagus. Humans have a larynx, skeleton, lymph nodes, bone marrrow and veins which sharks do not have in their anatomy. Sharks have a spiral valve intestine, cranial nerves and dorsal aorta. Researchers also found that about a dozen genes that help give rise to a shark’s median fins—those that run along its back and belly—also determine where paired side fins will form on its body. These genes are known to play important roles in the development of paired limbs in humans and other land animals. The genes come from an ancient ancestor shared by sharks and humans. The next thing I am going to compare is the digestive systems of humans and sharks.

Steps of Digestive System for Sharks and Humans

Step 1

Sharks: Digestion in the mouth= there is little physical digestion. Most sharks swallow their food whole or in very large pieces.

Humans: Mouth breaks down the food. There is continuous chewing which breaks down the food so that it is easily digested. Saliva mixes with food to begin the process of breaking down.

Step 2

Sharks: The food goes down the short and wide esophagus. It is hard to distinguish the esophagus from the stomach

Humans:Throat, also known as the pharynx, is the next step of digestion. Food travels to the esophagus. The Esophagus is a muscular tube that extends from the pharynx to the stomach. With a series of contractions, the food is delivered to the stomach.

Step 3

Sharks: Sharks have U-shaped Stomachs that use strong acids and enzymes to dissolve the food. The food that is not digested, like bone is thrown up.

Humans:The Stomach secretes acids and powerful enzymes that continue the process of breaking down the food. The food becomes a liquid or paste.

Step 4

Sharks: The stomach leads to the Intestines, which in sharks is referred to as the spiral valve. The intestines are short but have a large surface area. The digestive tract leads to the rectum and to the cloaca.

Humans:Small Intestine is the next step; it is made up of 3 segments, the duodenum, jejunum and ileum. The small intestine is a long tube that is loosely coiled in the abdomen. If measured it would be 20 feet long. The small intestine continues to break down the food by using enzymes released by the pancreas and bile from the liver. The duodenum plays a big role, with the jejunum and ileum. Being mainly responsible for the absorption of nutrients into the bloodstream.
Comparison

————————– Similarities:
• There are all the same components in the digestion other than a couple exceptions
• Strong acids and enzymes break down the food

——————————- Differences:
• there is physical digestion with humans and not sharks
• the shape of the esophagus
• Sharks stomachs are U-shaped, humans stomachs are a sac like organ
• Sharks intestines are short, humans are long

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