Amphibian Skin example essay topic

Index 1. What is an amphibian? 1.1 What is an ectotherm? 1.2 Diversity 1.2. 1 Anura 1.2. 2 Caudata 1.2.

3 Apoda 2. What is an amphibian like? 2.1 Structure 2.2 Appearance 3. How does an amphibian live?

3.1 Feeding Process 3.2 Reproduction 3.3 Adaptations 3.3. 1 Respiration 3.3. 1.1 Obligate Aerobes 3.3. 1.2 Obligate Anaerobes 3.3. 2 Endospores 4.

Importance 4.1 Ecological 4.2 Economical Amphibians What is an amphibian? The word amphibian comes from the Greek word 'amphibios' which means two lives: amphibians have a larval stage and an adult stage that are usually very different from each other. They are vertebrates, have thin, moist skin and four legs. They have no claws under toes. Nearly all of them rely on water for reproduction.

What is an ecotherm? Amphibians are most common in regions that have warm temperatures all year because they are ecotherms. An ecotherm is an animal in which the body temperature changes with the temperature of its surroundings. During such times, many amphibians burrow into the mud and stay there until suitable conditions return. Amphibians diversity They are classified and divided in 3 groups: o Anura - frogs and toads belong to this group, they are amphibians without tail. All adult frogs and toads eat insects.

Some frogs and toads produce toxins, they can kill predators; they also have vocal cords that are capable of producing a wide range of sounds. They spent part of their life cycle in water and part on land. o Caudata - salamanders belong to this order. A salamander has long, slender body with a neck and tail. They resemble lizards but have smooth, moist skin and lack claws.

They range in size from a few centimeters up to a size of 1.5 meters. Some are aquatic, and others live in damp places on land. o Apoda - Caecilians are limbless amphibians. Caecilians are amphibians that have no limbs, with a short, or no, tail. Caecilians are primarily tropical animals with small eyes that are often blind. They eat earthworms and other invertebrates found in the soil.

Metamorphosis Most amphibians go through the process of metamorphosis. Fertilized eggs hatch into tadpoles, the aquatic stage of most amphibians. Tadpoles possess fins, grills, and a two-chambered heart. As tadpoles grow into adult frogs and toads, they develop legs, lungs, and a three-chambered heart. Young salamanders resemble adults, but they have grills and usually have a tail fin. Most adult salamanders instead breathe through their moist skin, or with lungs.

Appearance o Physical Characteristics. - Most amphibians begin their lives as a larva, an immature form that has a significantly different body plan than that of an adult of the species. - Adult amphibians typically have body structures that enable them to move about on land as well as in the water. - Zoologists believe that adult frogs and toads do not have tails because they would be a hindrance in jumping. o Skin. Always hairless and rarely scaled, amphibian skin provides the animals with protective coloring, a way to absorb water and oxygen from their environments, and a defense against arid conditions and hungry predators. Amphibians use their permeable skin to obtain both oxygen and water from their environment.

Amphibian skin also contains glands that secrete a slimy mucous layer to protect the skin from drying out and help draw in oxygen through the skin. Internal Anatomy Amphibian internal anatomy is similar to that of other vertebrates. Adult amphibians typically have lungs, rather than gills, for breathing oxygen, but some water-dwelling species have both lungs and gills, and others obtain all the oxygen they need to survive through their permeable skin. Amphibians are cold-blooded, or more correctly, ecotherms-that is, they are not able to generate their own body heat. Instead, their body temperature is determined by their surroundings. Nervous System An amphibian has a brain and nervous system.

It has two eyes, with a third extra protective eyelid for when it is on land. -Central nervous system Cerebral hemispheres of brain are primarily olfactory centers 10 pairs of cranial nerves (vs. 12 in higher vertebrates) -Autonomic nervous system Simpler than higher vertebrates but same pattern Nerves control other systems Sense Organs Amphibians rely on their senses to find food and evade predators. Amphibians lack external ears but have well-developed internal ears. Hearing is most acute in frogs, which typically have a middle ear cavity for transferring sound vibrations from the eardrum, or tympanum, to the inner ear.

Frogs and toads also use their keen hearing in communicating with one another. Other sense organs include lateral line system, cutaneous receptor, as well as eyes and chemical receptors. Hearing and Vocalizations Amphibians lack external ears but have well-developed internal ears. Using a true voice box, or larynx, Frogs and toads also use their keen hearing in communicating with one another using a true voice box or larynx. Frogs have an expandable vocal sac attached to the throat which is used to increase the volume of their calls, which they use in mating and territorial disputes. Vision Vision is also critical for some amphibians.

Frogs have bulging eyes that protrude from either side of their head, enabling them to watch for danger and search for prey in nearly every direction. Caecilians, which live underground, are the only amphibians that are blind. Caecilians are equipped with eyes, but these are covered by skin and sometimes by bone. Behavior Much of an amphibian's lifestyle is dictated by the necessity of keeping its skin moist and preventing its body temperature from becoming too hot or too cold. Some species bask in the sun in order to raise their body temperature. In hotter climates, many adult amphibians are active at night rather than in the day to avoid excessive heat and guard against water loss.

During the daylight hours, these amphibians shelter in moist sites beneath rocks or logs, or in burrows or cracks in the earth. Defense Mechanism Their soft skin and lack of claws with which to defend themselves leave amphibians particularly vulnerable to their many predators, which include a host of small mammals, birds, lizards, snakes, turtles, and even larger amphibians. When facing a predator, many amphibians pretend to be dead. Other amphibians rely on toxins in their skin to give them a bad taste or make them poisonous to predators. To warn predators of their poisonous glands, these amphibians often are brightly colored or able to change their color in the face of danger. Circulatory System The evolution of the three-chambered heart in amphibians ensured that cells received the proper amount of oxygen.

This heart was an important evolutionary transition from the simple circulatory system of fishes. In the three-chambered heart, one chamber receives oxygen rich blood from the lungs and skin, and another receives oxygen poor blood from the body tissues. Blood from both chambers then moves to the lungs and skin so it can pick up more oxygen. This results in some mixing of some oxygen rich and oxygen poor blood in the amphibian heart and in blood vessels leading away from the heart.

Thus, in amphibians, the skin is much more important than the lungs as an organ for gas exchange. Digestive Track The amphibian digestive system consists of a mouth, esophagus, stomach, and intestine, which opens into a chamber at their posterior called the cloaca. Digestive wastes are processed by the kidneys, excreted into the cloaca, then expelled from the body through a muscular opening in the cloaca. This opening is also where eggs and sperm exit the body. Skeleton An amphibian has an inner skeleton with a backbone.

It has webbed feet, but no claws. They have attached limbs at the shoulders and hips. With the frog and toad, the front legs are shorter and weaker and the rear legs much stronger for leaping. How do they move? During the first stages of its life amphibians they use their tail to swim and move trough its environment, later legs will grow and they will use them to jump on land and swim.

Frogs have the rear legs are much larger and stronger than the front legs for leaping. Biology, Dynamics of Life Pages 828-832.