23.+chordata-++mammalia+-+monotreme

Chordata- Mammalia - Monotreme PLATYPUS Russell Rapaport

= Classification/Diagnostic characteristics =
 * The platypus is a monotreme, meaning it is a mammal that lays eggs. Its body and flat tail are colored brown by fur which insulates the creature by maintaining a layer of air trapped around it. Describes as similar to a mole, the skin of the platypus is waterproof. Like the Tasmanian devil, the platypus stores copious amounts of fat in its tail. It has webbed feet, but its front feet are much more webbed than its back, so it can walk on land. The snout of a platypus differs from the beak of a bird in the sense that it is a sensory organ and its mouth is on the underside. They make various noises, but most notable is a growl when they feel threatened. (1)
 * The body and the broad, flat tail of the platypus are covered with dense, brown [|fur] that traps a layer of insulating air to keep the animal warm.
 * To be a mammal, each of the following must be true:
 * sweat glands, which secrete sweat to cool an animal
 * mammary glands, which in females secrete milk
 * hair, which provides an insulating covering
 * a four-chambered heart

**Relationship to humans**
 * In the same genus as humans
 * The platypus's genome comprises of 2/3 the amount of genes as humans
 * Platypuses avoid contact with humans
 * In the past, humans have killed platypuses and used their fur
 * However, now the platypus is a protected native species


 * Predation Avoidance **

= Habitat and niche = = Nutrient acquisition = = = = Reproduction and life cycle = **Growth and development**
 * Male platypuses have a poisonous spur in theback of their ankle
 * This spur is connected to. venom gland and is 15 mm long
 * In water, the platypus is extremely fast, and can swim fast to avoid most of its aquatic predators
 * On land, the platypus uses its spur to inject poison into its predators
 * The venom in the spur is strong enough to kill a small animal
 * Predators of platypuses include foxes, dogs, snakes, feral cats, and large eels (17)
 * Platypuses are usually found in places with large bodies of water, that also have roots, overhanging vegetation, reeds, and logs
 * Platypuses often construct burrows
 * The platypus usually lives in streams that around around five meters deep.
 * Female platypuses usually make two burrows, one for themselves and their mate, and another for their children
 * Platypuses live in dirt burrows near the edge of bodies of water in Australia (8)
 * they are usually found in Austrailia, tasmania, and New Guinea (2)
 * Platypuses hunt for insects, shellfish, worms, larvae, and gravel underwater. Since they don't have teeth, they swish the mixture around in their cheek pouches and use the gravel to break up their food (8)
 * Platypuses use their beak to shovel up invertebrates from stream or lake bends; they eat frogs. fish or insects from the water's surface. (8)
 * They acquire their nutrients through the detection of electrical signals
 * lay eggs for reproduction
 * The duckbill platypus is a monotreme, or egg laying mammal, that begins to reproduce at four years of age. Gestation takes 2-4 weeks at which time the female typically lays 2 eggs and incubates the eggs for approximately 6-10 days until the eggs hatch. The platypus reaches its adult size in 12-18 months and have a relatively long life for small mammals, living up to 20 years in the wild.
 * the eggs are fertilized internally
 * females seal themselves inside their burrow in order to lay their eggs
 * mothers keep their eggs warm by holding them in between their tail and body
 * the mother platypus nurse their young for 3-4 months until the babies can survive and swim on their own
 * one of only two mammals that lays eggs (5) (9)
 * Platypus typically mate from July to October, and their eggs are laid one month later
 * Gestation: females lay 2-3 soft-shelled eggs
 * Egg Development: incubation lasts about 6-10 days
 * Hatching: their forelimbs have clawed digits and their hindlimb are paddles; a yolk sac is present
 * Young: platypus feed on the milk from their mother for 4 months while living in a river burrow (18)

**Integument**
 * around their eyes and ears, they have deep folds so water does not get inside while they are swimming
 * most notable feature about the integumentary system of mammals is the presence of hair (7)
 * hair can be used as sensory organs in some animals, but usually serve as a method of insulation
 * mammalian epidermis has several layers of skin cells
 * often has horny or bony structures, such as nails/claws, hooves, quills, horns, etc.
 * mammals have special glandular units devoted to the secretion of specific odors for communication or for sexual signaling
 * the mating habits of many mammals depend on odor secretion glands
 * platypus has webbed feet which allows it to swim more easily
 * sleek fur allows for it to swim and glide through water without dampening too much
 * duck-billed platypus has poison secretion glands on openings on the spine of each hind foot - this also plays a large role in predator avoidance (11)

= Movement = = Sensing the environment =
 * the platypus has short legs, a duck-bill, webbed feet, flat tail
 * webbed feet end in claws, so it can be used for padding and movement like that
 * skin can fold back around the feet so that it can dig (6)
 * They use their bills to detect prey and to help them navigate in murky water. (8)
 * The bill is soft, flexible and covered with sensory receptors that can detect electrical and tactile stimuli. (8)
 * Platypuses are most active at night and spend the days resting in their burrows. (8)
 * Their eyes are covered by folds of skin and ears underwater so that water doesn't come in. Additionally, the nostrils close.
 * Platypus, along with echidnas, possess a unique electromechanical system of electroreceptors and touch receptors that allow it navigate underwater flawlessly even though its senses of sight, smell, and hearing are basically shut off while it's submerged. (16)

= Gas exchange = = = = Waste removal =
 * As like all animals in Mammalia, the platypus possess two lungs and a four-chambered heart that form a systemic and pulmonary circuit, pumping deoxygenated blood through capillaries that are in turn wrapped around alveoli, the primary gas exchange surface. Despite spending much time foraging underwater, platypi do not have the ability to breathe underwater. Rather, they have openings in the top of their bills that allow gases to enter and leave only when above water; thus, the animal can spend time swimming on top of a water body before closing its openings and diving below. Infants are not developed enough to operate this system lest they drown, but developed adults can spend up two minutes underwater on average. (13) (14) (15)
 * use kidneys for excretion
 * the platypus also has a cloaca, an opening through which feces, urine, and sperm or eggs pass (6)
 * Platypuses mainly excretes its nitrogenous wastes in the form of urea

= Environmental physiology (temperature, water and salt regulation) =
 * they are able to regulate their water and salt levels through their excretory system
 * use sweat to regulate high temperatures
 * the platypus is homeothermic, meaning that it maintains its low body temperature of 32 degrees celsius
 * Platypuses are mostly nocturnal in their foraging
 * They can maintain their bodies even in 5 degrees celsius water for several hours (19)

= Internal circulation =
 * use a four-chambered heart and lungs for diffusion
 * closed double looped circ. system
 * same type of system as humans: heart, arteries, veins, etc.
 * blood flow is the same too: right atrium, rigtht ventricle, pulmonic circuit, left atrium, left ventricle, systemic circuit and repeat. (12)

**Chemical control (i.e. endocrine system)**
 * The Platypus's endocrine system, along with its nervous system, are able to maintain homeostasis
 * All the chemical systems in the platypus communicate with each other and let them know when a condition must be changed (12)

1) Although they have a standard mammalian cardiovascular/pulmonary system with 2 lungs and a 4-chambered heart, they spend most of their time underwater but cannot breathe. How do they maintain gas exchange when underwater? (//Although platypuses don't breathe underwater, they have openings in the top of their bills that allow for gas to enter, and then leave once the platypus goes above water. As a result, platypuses can spend up to two minutes underwater at a time.)//
 * Review Questions:**

2) What adaptations allow platypuses to sense their environment what their traditional senses like sight, smell, and hearing are rendered ineffective? //(Platypuses have a specialised sensory organ in their bill for detecting electrical impulses, in addition to highly developed sense of touch.)//

//3)// How are platypuses able to defend themselves from their land predators, such as foxes, snakes, and dogs? (Male p//latypuses have developed a unique adaptation called a spur in their ankle. This spur contains venom, and is extremely poisonous. As a result, a platypus can kill small animals and injure larger ones with a poisonous spur.)//

4) Describe the growth and development of platypuses through multiple phases of their lives. (//First, during the gestation phase, the female platypus lays 2-3 eggs. Then, the eggs develop for 6-10 days during incubation. Next, the platypuses hatch from their eggs. Finally, during youth, platypuses feed off their mother's milk for 3-4 months while living in a river burrow.//

5) Platypuses can be found both in the water and on land. Where specifically are the platypuses habitats? (//Often, platypuses contract burrows and live near rivers. They usually live in streams that are around five feet deep. Most platypuses are found in Australia, New Guinea, and Tasmania.)//

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