Agriculture
Got Milk? How?
Middle school science adventures
Hungry bug seeks hot meal
Amphibians
Toads
Tree Frogs
Poison Dart Frogs
Animals
Insects Take a Breather
Putting a Mouse on Pause
Dolphin Sponge Moms
Behavior
Dino-bite!
A Light Delay
Internet Generation
Birds
Peafowl
Parakeets
Birds We Eat
Chemistry and Materials
The hottest soup in New York
The Incredible Shrunken Kids
Sweeeet! The Skinny on Sugar Substitutes
Computers
A New Look at Saturn's rings
Batteries built by Viruses
Fingerprint Evidence
Dinosaurs and Fossils
From Mammoth to Modern Elephant
Downsized Dinosaurs
Ferocious Growth Spurts
E Learning Jamaica
Results of GSAT are in schools this week
2014 GSAT Results for Jamaican Kids
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
Earth
A Global Warming Flap
Slip Slidin' Away—Under the Sea
Giving Sharks Safe Homes
Environment
Groundwater and the Water Cycle
Watching for Wildfires in Yellowstone
Acid Snails
Finding the Past
Fakes in the museum
Watching deep-space fireworks
Stone Age Sole Survivors
Fish
Codfish
Flashlight Fishes
Electric Ray
Food and Nutrition
Eat Out, Eat Smart
Food for Life
Turning to Sweets, Fats to Calm the Brain
GSAT English Rules
Adjectives and Adverbs
Who vs. Whom
Problems with Prepositions
GSAT Exam Preparation Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
GSAT Scholarship
Scotiabank Jamaica Foundation Grade Six Achievement Test (GSAT) Scholarships
GSAT Exams Jamaica Scholarships
Access denied - Disabled boy aces GSAT
GSAT Exam Preparation
Results of GSAT are in schools this week
GSAT Mathematics
10 Common Mistakes When Preparing for the GSAT Math Test
Secrets of an Ancient Computer
GSAT Mathematics Quiz, Teaching Math, teaching anxiety
Human Body
Workouts: Does Stretching Help?
Sea Kids See Clearly Underwater
Teen Brains, Under Construction
Invertebrates
Fleas
Bedbugs
Sea Urchin
Mammals
Otters
Bison
Flying Foxes
Parents
What Not to Say to Emerging Readers
How children learn
Raise a Lifelong Reader by Reading Aloud
Physics
One ring around them all
IceCube Science
Road Bumps
Plants
Bright Blooms That Glow
White fuzzy mold not as friendly as it looks
Plants Travel Wind Highways
Reptiles
Copperhead Snakes
Box Turtles
Crocodilians
Space and Astronomy
Melting Snow on Mars
A Family in Space
Cousin Earth
Technology and Engineering
Switchable Lenses Improve Vision
A Satellite of Your Own
Are Propellers Fin-ished?
The Parts of Speech
Pronouns
What is a Verb?
What is a Noun
Transportation
Robots on the Road, Again
Troubles with Hubble
Where rivers run uphill
Weather
Antarctica warms, which threatens penguins
In Antarctica watch the heat (and your step)
Either Martians or Mars has gas
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™