Agriculture
Microbes at the Gas Pump
Chicken Eggs as Drug Factories
Where Have All the Bees Gone?
Amphibians
Bullfrogs
Frogs and Toads
Newts
Animals
Eyes on the Depths
Stunts for High-Diving Ants
Pothole Repair, Insect-style
Behavior
Puberty gone wild
Bringing fish back up to size
The nerve of one animal
Birds
Crows
Ibises
Vultures
Chemistry and Materials
Getting the dirt on carbon
Unscrambling a Gem of a Mystery
The solar system's biggest junkyard
Computers
A Classroom of the Mind
Middle school science adventures
Fingerprint Evidence
Dinosaurs and Fossils
The bug that may have killed a dinosaur
Ancient Critter Caught Shedding Its Skin
Big Fish in Ancient Waters
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
Sky Dust Keeps Falling on Your Head
Digging into a Tsunami Disaster
Snowflakes and Avalanches
Environment
Missing Tigers in India
Nanosponges Soak Up Pollutants
Improving the Camel
Finding the Past
Words of the Distant Past
Early Maya Writing
A Long Trek to Asia
Fish
Skates
Basking Sharks
Tuna
Food and Nutrition
The Color of Health
How Super Are Superfruits?
Making good, brown fat
GSAT English Rules
Finding Subjects and Verbs
Subject and Verb Agreement
Who vs. Whom
GSAT Exam Preparation Jamaica
Results of GSAT are in schools this week
March 21-22, 2013: Over 43,000 students will take the GSAT Exam
Tarrant High overcoming the odds
GSAT Exams Jamaica Scholarships
Access denied - Disabled boy aces GSAT
GSAT Scholarship
2014 GSAT Results for Jamaican Kids
GSAT Mathematics
Detecting True Art
A Sweet Advance in Candy Packing
Losing with Heads or Tails
Human Body
Workouts: Does Stretching Help?
Heart Revival
A New Touch
Invertebrates
Clams
Tapeworms
Shrimps
Mammals
Lion
Gazelle
Cheetah
Parents
How children learn
Raise a Lifelong Reader by Reading Aloud
The Surprising Meaning and Benefits of Nursery Rhymes
Physics
Hold on to your stars, ladies and gentlemen
The Pressure of Scuba Diving
Electric Backpack
Plants
City Trees Beat Country Trees
Stalking Plants by Scent
A Giant Flower's New Family
Reptiles
Lizards
Snakes
Chameleons
Space and Astronomy
Saturn's New Moons
A Puffy Planetary Puzzle
Solving a Sedna Mystery
Technology and Engineering
Sugar Power for Cell Phones
Supersuits for Superheroes
Spinach Power for Solar Cells
The Parts of Speech
What is a Noun
Problems with Prepositions
Pronouns
Transportation
Are Propellers Fin-ished?
Ready, unplug, drive
Troubles with Hubble
Weather
Watering the Air
Earth's Poles in Peril
Antarctica warms, which threatens penguins
Add your Article

Sea Anemones

Named after a terrestrial flower, the anemone, sea anemones form a group of water-dwelling, filter feeding animals of the order Actinaria. As a cnidarian, the sea anemone is closely related to coral and jellyfish. Other close relations to the sea anemone are the solitary, tube-dwelling anemones and the hydras. Sea flowers: An anemone is basically the typical polyp: a small sac, attached to the bottom by an adhesive foot, with a column shaped body ending in an oral disc. The mouth is in the middle of the oral disc, surrounded by tentacles armed with many cnidocytes, which are unique cells that function as a defense and as a means to capture prey. Toxic hairs: Cnydocytes contain cnidae, capsule-like organelles capable of everting, giving phylum Cnidaria its name . The cnidae that sting are called nematocysts. Each nematocyst contains a small vesicle filled with toxins— actinoporins— an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion, that fires a harpoon-like structure which attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. Sticky, but not toxic to all: This gives the anenome its characteristic sticky feeling. Interestingly the clownfish is immune to an anenome's sting. The poison is actually a mix of toxins, including neurotoxins, which serve to paralyze and capture the prey, which is then moved by the tentacles to the mouth/anus for digestion inside the gastrovascular cavity. Actinoporins have been reported as highly toxic to fish and crustaceans, which may be the natural prey of sea anemones. In addition to their role in predation, it has been suggested that actinoporins could act, when released in water, as efficient repellents against potential predators. Internal anatomy: The internal anatomy of anemones is very simple. There is a gastrovascular cavity (which functions as a stomach) with a single opening to the outside which fuctions as both a mouth and an anus: waste and undigested matter is excreted through the mouth/anus. A primitive nervous system, without centralization, coordinates the processes involved in maintaining homeostasis as well as biochemical and physical responses to various stimuli. Anemones range in size from less than 1¼ cm (½ in) to nearly 2 m (6 ft) in diameter. They can have a range of 10 tentacles to hundreds. Parasite: A few anemones are parasitic to marine organisms. Anemones tend to stay in the same spot unless they are unhappy with that location, or a predator is attacking them. In the case of an attack, anemones can uproot themselves and swim away to a new location, using flexing motions. Attachment: The sea anemone has a foot which in most species attaches itself to rocks or anchors in the sand. Some species attach to kelp and others are free-swimming. Although not plants and therefore incapable of photosynthesis themselves, many sea anemones form an important symbiosis with certain single-celled green algae species which reside in the animals' gastrodermal cells. These algae may be either zooxanthellae, zoochlorellae or both. The sea anemone benefits from the products of the algae's photosynthesis, namely oxygen and food in the form of glycerol, glucose and alanine; the algae in turn are assured a reliable exposure to sunlight, which the anemones actively maintain. The preponderance of species inhabit tropical reefs, although there are species adapted to relatively cold waters, intertidal reefs, and sand/kelp environments. Symbiotic relationships: Some sea anemones form symbiotic relationships with crabs or with anemone fish, also known as clownfish. In the former situation, anemones will either attach or be attached to the shell of a hermit crab (by the crab's own volition), providing additional protection for the crab and allowing the anemone to eat scraps when the crab feeds. A similar relationship can be formed between a sea anemone and a clownfish. The clownfish presses itself into the anemone, living comfortably within the stinging tentacles. This is possible because of a protective mucus that covers the clownfish. It is not yet fully understood whether the protective mucus impedes the nemtocysts from penetrating the flesh of the clownfish or if the mucus supresses nematocysts from firing. The clownfish benefits from this symbiotic relationship because it is protected by the anemone and in turn the anemone benefits because it gets food scraps from the clownfish. Muscles and nerves: The muscles and nerves in anenomes are much simpler than those of other animals. Cells in the outer layer (epidermis) and the inner layer (gastrodermis) have microfilaments grouped together into contractile fibers. These are not true muscles because they are not freely suspended in the body cavity as they are in more developed animals. Since the anemone lacks a skeleton, the contractile cells pull against the gastrovascular cavity, which acts as a hydrostatic skeleton. The stability for this hydrostatic skeleton is caused by the anemone shutting its mouth closed, which keeps the gastrovascular cavity at a constant volume, making it more rigid. Fossils: Most Actinaria do not form hard parts that can be recognized as fossils but a few fossils do exist; Mackenzia, from the Middle Cambrian Burgess Shale of Canada, is the oldest fossil identified as a sea anemone. Unlike other cnidarians, anemones (and other anthozoans) entirely lack the free-swimming medusa stage of the life cycle: the polyp produces eggs and sperm, and the fertilized egg develops into a planula that develops directly into another polyp. Separate sexes: The sexes in sea anemones are separate. Both sexual and asexual reproduction may occur. In sexual reproduction males release sperm which stimulates females to release eggs, and fertilization occurs. The eggs or sperm are ejected through the mouth. The fertilized egg develops into a planula, which finally settles down somewhere and grows into a single anemone. They can also reproduce asexually by budding, binary fission, which involves pulling apart into two halves, and pedal laceration, in which small pieces of the pedal disc break off and regenerate into small anemones. Laceration is a process of fragmentation of the basal disk, or by pulling itself into two parts.

Sea Anemones
Sea Anemones








Designed and Powered by HBJamaica.com™