Agriculture
Springing forward
Earth-Friendly Fabrics
Getting the dirt on carbon
Amphibians
Toads
Tree Frogs
Frogs and Toads
Animals
Ants on Stilts
Living in the Desert
A Sense of Danger
Behavior
Seeing red means danger ahead
Island of Hope
Baby Talk
Birds
Macaws
Cardinals
Pelicans
Chemistry and Materials
Gooey Secrets of Mussel Power
Earth-Friendly Fabrics
Scientist Profile: Wally Gilbert
Computers
Play for Science
The hungry blob at the edge of the universe
Earth from the inside out
Dinosaurs and Fossils
An Ancient Spider's Web
A Really Big (but Extinct) Rodent
Meet your mysterious relative
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
On the Trail of America's Next Top Scientists
Riding to Earth's Core
Pollution at the ends of the Earth
Environment
The Oily Gulf
Fungus Hunt
Out in the Cold
Finding the Past
Unearthing Ancient Astronomy
Chicken of the Sea
Oldest Writing in the New World
Fish
Bull Sharks
Basking Sharks
Sharks
Food and Nutrition
Strong Bones for Life
Moving Good Fats from Fish to Mice
Allergies: From Bee Stings to Peanuts
GSAT English Rules
Order of Adjectives
Pronouns
Capitalization Rules
GSAT Exam Preparation Jamaica
Tarrant High overcoming the odds
March 21-22, 2013: Over 43,000 students will take the GSAT Exam
The Annual GSAT Scholarships
GSAT Exams Jamaica Scholarships
Results of GSAT are in schools this week
GSAT Practice Papers | GSAT Mathematics | Maths
42,000 students will sit for the GSAT Exam in two weeks
GSAT Mathematics
Math of the World
A Sweet Advance in Candy Packing
Losing with Heads or Tails
Human Body
Kids now getting 'adult' disease
Flu Patrol
Germ Zapper
Invertebrates
Worms
Insects
Starfish
Mammals
Opposum
Rodents
Badgers
Parents
Choosing a Preschool: What to Consider
Expert report highlights the importance to parents of reading to children!
What Not to Say to Emerging Readers
Physics
Speedy stars
Thinner Air, Less Splatter
One ring around them all
Plants
Nature's Alphabet
City Trees Beat Country Trees
Flower family knows its roots
Reptiles
Tortoises
Box Turtles
Rattlesnakes
Space and Astronomy
Black Holes That Burp
Planet Hunters Nab Three More
Sounds of Titan
Technology and Engineering
Model Plane Flies the Atlantic
Dancing with Robots
Space Umbrellas to Shield Earth
The Parts of Speech
Problems with Prepositions
What is a Verb?
Pronouns
Transportation
Ready, unplug, drive
Reach for the Sky
Revving Up Green Machines
Weather
The Best Defense Is a Good Snow Fence
Arctic Melt
Earth's Poles in Peril
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™