Agriculture
Getting the dirt on carbon
Watching out for vultures
Vitamin D-licious Mushrooms
Amphibians
Tree Frogs
Toads
Salamanders
Animals
Mating Slows Down Prairie Dogs
From Chimps to People
A Seabird's Endless Summer
Behavior
Fish needs see-through head
The Snappy Lingo of Instant Messages
How Much Babies Know
Birds
Ospreys
Penguins
Hummingbirds
Chemistry and Materials
The hottest soup in New York
The science of disappearing
Screaming for Ice Cream
Computers
Middle school science adventures
Electronic Paper Turns a Page
A Classroom of the Mind
Dinosaurs and Fossils
A Rainforest Trapped in Amber
Have shell, will travel
Fossil Forests
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
Earth
Wave of Destruction
Watering the Air
Arctic Algae Show Climate Change
Environment
Flu river
Blooming Jellies
Alien Invasions
Finding the Past
Sahara Cemetery
Little People Cause Big Surprise
Preserving Ancient Warrior Paint
Fish
Hammerhead Sharks
Skates and Rays
Tilapia
Food and Nutrition
Sponges' secret weapon
Recipe for Health
The mercury in that tuna
GSAT English Rules
Who vs. That vs. Which
Who vs. Whom
Adjectives and Adverbs
GSAT Exam Preparation Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
GSAT Exam Preparation
GSAT stars reap scholarship glory
GSAT Exams Jamaica Scholarships
GSAT Scholarship
Access denied - Disabled boy aces GSAT
GSAT Practice Papers | GSAT Mathematics | Maths
GSAT Mathematics
Math Naturals
Deep-space dancers
Setting a Prime Number Record
Human Body
Spit Power
Cell Phone Tattlers
Sea Kids See Clearly Underwater
Invertebrates
Flatworms
Sea Urchin
Horseshoe Crabs
Mammals
Gerbils
Mouse
Moles
Parents
Children and Media
The Surprising Meaning and Benefits of Nursery Rhymes
Choosing a Preschool: What to Consider
Physics
Thinner Air, Less Splatter
Strange Universe: The Stuff of Darkness
Electric Backpack
Plants
Tracking the Sun Improves Plant Pollen
The algae invasion
Fast-flying fungal spores
Reptiles
Asp
Copperhead Snakes
Crocodiles
Space and Astronomy
Icy Red Planet
Pluto, plutoid: What's in a name?
Gravity Tractor as Asteroid Mover
Technology and Engineering
Bionic Bacteria
Musclebots Take Some Steps
Squeezing Oil from Old Wells
The Parts of Speech
What is a Verb?
Problems with Prepositions
Adjectives and Adverbs
Transportation
Charged cars that would charge
Tinkering With the Basic Bike
Robots on the Road, Again
Weather
The Best Defense Is a Good Snow Fence
A Change in Climate
Recipe for a Hurricane
Add your Article

Crustaceans

Picture your last seafood meal, and you're probably seeing a crustacean. Crustaceans are mostly water-dwelling invertebrates (no spine), characterized by a jointed body and limbs, and a hard outer shell called an exoskeleton. Although some species live on land, the most common and identifiable crustaceans are ocean-dwellers, such as lobsters, crabs, and even shrimp and barnacles. The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. They include various familiar animals, such as lobsters, crabs, shrimp and barnacles. The majority are aquatic, living in either fresh water or marine environments, but a few groups have adapted to terrestrial life, such as terrestrial crabs, terrestrial hermit crabs and woodlice. The majority are motile, although a few taxa are parasitic and live attached to their hosts (including sea lice, fish lice, whale lice, tongue worms, and Cymothoa exigua), and adult barnacles live a sessile life, attached head-first to the substrate. The scientific study of crustaceans is known as carcinology. Other names for carcinology are malacostracology, crustaceology and crustalogy, and a scientist who works in carcinology is a carcinologist, crustaceologist or crustalogist. Crustaceans have three distinct body parts: head, thorax, and abdomen (or pleon), although the head and thorax may fuse to form a cephalothorax. The head bears two pairs of antennae, one pair of compound eyes and three pairs of mouthparts. The thorax and pleon bear a number of lateral appendages, including the gills, and the tail ends with a telson. Smaller crustaceans respire through their body surface by diffusion, and larger crustaceans respire with gills or, with abdominal lungs In common with other arthropods, crustaceans have a stiff exoskeleton which must be shed to allow the animal to grow (ecdysis). Various parts of the exoskeleton may be fused together; this is particularly noticeable in the carapace, the thick dorsal shield seen on many crustaceans. Crustacean appendages are typically biramous; this includes the second pair of antennae, but not the first, which is uniramous. There is some doubt whether this is an advanced state, as had been traditionally assumed, or whether it may be a primitive state, with the branching of the limbs being lost in all extant arthoropod groups except the crustaceans. One piece of evidence supporting the latter view is the biramous nature of trilobite limbs. Although a few are hermaphroditic, most crustaceans have separate sexes, which are distinguished by appendages on the abdomen called swimmerets or, more technically, pleopods. The first (and sometimes the second) pair of pleopods are specialised in the male for sperm transfer. Many terrestrial crustaceans (such as the Christmas Island red crab) mate seasonally and return to the sea to release the eggs. Others, such as woodlice lay their eggs on land, albeit in damp conditions. In many decapods, the eggs are retained by the females until they hatch into free-swimming larvae. Those crustaceans that have hard exoskeletons reinforced with calcium carbonate, such as crabs and lobsters tend to preserve well as fossils, but many crustaceans have only thin exoskeletons. Most of the fossils known are from coral reef or shallow sea-floor environments, but many crustaceans live in open seas, on deep sea-floors or in burrows. Crustaceans tend, therefore, to be rarer in the fossil record than trilobites. Some crustaceans are reasonably common in Cretaceous and Caenozoic rocks, but barnacles have a particularly poor fossil record, with very few specimens from before the Mesozoic era.

Crustaceans
Crustaceans








Designed and Powered by HBJamaica.com™