Agriculture
Cleaning Up Fish Farms
Middle school science adventures
Flush-Free Fertilizer
Amphibians
Salamanders and Newts
Newts
Bullfrogs
Animals
Bee Heat Cooks Invaders
Hearing Whales
Feeding School for Meerkats
Behavior
A brain-boosting video game
The Snappy Lingo of Instant Messages
Calculating crime
Birds
Pheasants
Songbirds
Turkeys
Chemistry and Materials
Screaming for Ice Cream
Sticky Silky Feet
Small but WISE
Computers
Toxic Dirt + Avian Flu = Science Fair Success
Electronic Paper Turns a Page
Computers with Attitude
Dinosaurs and Fossils
Meet your mysterious relative
From Mammoth to Modern Elephant
Did Dinosaurs Do Handstands?
E Learning Jamaica
2014 GSAT Results for Jamaican Kids
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
Results of GSAT are in schools this week
Earth
The Rise of Yellowstone
Groundwater and the Water Cycle
A Dire Shortage of Water
Environment
Indoor ozone stopper
Power of the Wind
Food Web Woes
Finding the Past
Stonehenge Settlement
Your inner Neandertal
Digging Up Stone Age Art
Fish
Nurse Sharks
Skates and Rays
Whale Sharks
Food and Nutrition
Making good, brown fat
Healing Honey
Allergies: From Bee Stings to Peanuts
GSAT English Rules
Whoever vs. Whomever
Subject and Verb Agreement
Capitalization Rules
GSAT Exam Preparation Jamaica
GSAT Scholarship
Scotiabank Jamaica Foundation Grade Six Achievement Test (GSAT) Scholarships
GSAT stars reap scholarship glory
GSAT Exams Jamaica Scholarships
GSAT Exam Preparation
Access denied - Disabled boy aces GSAT
GSAT stars reap scholarship glory
GSAT Mathematics
Deep-space dancers
GSAT Practice Papers | GSAT Mathematics | Maths
GSAT Mathematics Quiz, Teaching Math, teaching anxiety
Human Body
Nature's Medicines
Kids now getting 'adult' disease
Speedy Gene Gives Runners a Boost
Invertebrates
Walking Sticks
Moths
Lobsters
Mammals
Miniature Schnauzers
African Gorillas
Rats
Parents
The Surprising Meaning and Benefits of Nursery Rhymes
Children and Media
How children learn
Physics
Road Bumps
Strange Universe: The Stuff of Darkness
IceCube Science
Plants
Farms sprout in cities
White fuzzy mold not as friendly as it looks
Cactus Goo for Clean Water
Reptiles
Cobras
Turtles
Pythons
Space and Astronomy
Zooming In on the Wild Sun
Big Galaxy Swallows Little Galaxy
Galaxies Divide Sharply Along Color Lines
Technology and Engineering
Beyond Bar Codes
Spinach Power for Solar Cells
Musclebots Take Some Steps
The Parts of Speech
What is a Preposition?
Countable and Uncountable Nouns
What is a Noun
Transportation
Tinkering With the Basic Bike
Middle school science adventures
Seen on the Science Fair Scene
Weather
Arctic Melt
Weekend Weather Really Is Different
Watering the Air
Add your Article

Marsupials

Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name 'Marsupial' derives) in which it rears its young through early infancy. They differ from placental mammals (Placentalia) in their reproductive traits. The female has two vaginas, both of which open externally through one orifice but lead to different compartments within the uterus. Males usually have a two-pronged penis which corresponds to the females' two vaginas. The penis only passes sperm. Marsupials have a cloaca [1] [2] that is connected to a urogenital sac in both sexes. Waste is stored there before expulsion. The pregnant female develops a kind of yolk sack in her womb which delivers nutrients to the embryo. The embryo is born at a very early stage of development (at about 4-5 weeks), upon which it crawls up its mother's belly and attaches itself to a nipple. It remains attached to the nipple for a number of weeks. The offspring later passes through a stage where it temporarily leaves the pouch, returning for warmth and nourishment. Fossil evidence, first announced by researcher M.J. Spechtt in 1982, does not support the once-common belief that marsupials were a primitive forerunner of the placental mammals: both main branches of the mammal tree appear to have evolved at around the same time, toward the end of the Mesozoic era, and have been competitors since that time. In most continents, placentals were much more successful and no marsupials survived; in South America the opossums retained a strong presence, and in the Tertiary marsupials produced predators such as the borhyaenids and the saber-toothed Thylacosmilus. In Australia placental mammals were not present throughout much of the Tertiary and marsupials and monotremes dominated completely. Native Australian placental mammals are more recent immigrants (e.g., the hopping mice). The early birth of marsupials removes the developing young much sooner than in placental mammals, and marsupials have not needed to develop a complex placenta to protect the young from its mother's immune system. Early birth places the tiny new-born marsupial at greater risk, but significantly reduces the risks associated with pregnancy, as there is no need to carry a large fetus to full-term in bad seasons. Because a newborn marsupial must climb up to its mother's nipples, the otherwise minimally developed newborn has front limbs that are much better developed than the rest of its body. This requirement is responsible for the more limited range of locomotory adaptations in marsupials than placentals; marsupials must retain a grasping forepaw and cannot develop it into a hoof, wing, or flipper as some groups of placental mammals have done. There are about 334 species of marsupials, over 200 of them native to Australia and nearby islands to the north. There are also many extant species in South America and one species, the Virginia Opossum, native to North America. Most marsupials are slow moving creatures but kangaroos can reach speeds of up to 31mph (50km/h).

Marsupials
Marsupials








Designed and Powered by HBJamaica.com™