Class: Scyphozoa
The class name Scyphozoa comes from the Greek word skyphos, denoting a kind of drinking cup and alluding to the cup shape of the animal.
Phylum: Cnidaria
Kingdom: Animalia
Jellyfish: transparent, soft-bodied marine animal, umbrella-shaped and of gelatinous appearance.
Umbrella: main part of the body of a jellyfish.
Endoderm: part of the jellyfish that supplies its digestive and respiratory systems.
Stomach: digestive organ of a jellyfish.
Gonad: sexual gland of a jellyfish.
Testis: sac containing the genital organs of a jellyfish.
Tentacle: organ of touch of a jellyfish.
Manubrium canal: tube situated in the foot of a jellyfish.
Oral arms: limb of the jellyfish related to its mouth.
Mouth: entrance to the digestive tract of a jellyfish.
Subumbrella: lower part of the umbrella of a jellyfish.
Radial canal: tube that follows a ray of the umbrella of a jellyfish.
Tentacles: mouth of a jellyfish.
Sense organ: sensory organ of a jellyfish.
They are made up of a layer of epidermis, gastrodermis, and a thick jellylike layer called mesoglea that separates the epidermis from the gastrodermis.
To compensate for its lack of basic sensory organs and a brain, the jellyfish exploits its nervous system and rhopalia to perceive stimuli, such as light or odor, and orchestrate expedient responses.
Their shape is not hydrodynamic, which makes them slow swimmers but this is little hindrance as they feed on plankton, needing only to drift slowly through the water. It is more important for them that their movements create a current where the water (which contains their food) is being forced within reach of their tentacles. They accomplish this by rhythmically opening and closing their bell-like body.
Holding jellies in captivity also presents other problems: for one, they are not adapted to closed spaces or areas with walls, which aquariums by definition have.
A group of jellyfish is often called a "smack." Many species of jellyfish are also capable of congregating into large swarms or "blooms" consisting of hundreds or even thousands of individuals. The formation of these blooms is a complex process that depends on ocean currents, nutrients, temperature and oxygen content. Jellyfish will sometimes mass breed during blooms. Jellyfish population is reportedly raising major ecological concerns for a possible jellyfish outbreak.
Most jellyfish have tentacles or oral arms coated with thousands of microscopic nematocysts; generally, each of these nematocyst has a "trigger" (cnidocil) paired with a capsule containing a coiled stinging filament, as well as barbs on the exterior. Upon contact, the filament will swiftly unwind, launch into the target, and inject toxins. It can then pull the victim into its mouth, if appropriate.
Abstract
The effects of ten different water temperatures on the growth of newly released ephyrae of Aurelia labiata were explored. Ephyrae grown at 21°C showed the greatest growth, increasing in bell diameter from about 4.0 mm to 14.5 mm in 14 days and remained in good condition for the duration of the experiment. Ephyrae subjected to other temperatures grew at different rates. Ephyrae maintained at 8°C gradually decreased in size during the experiment, shrinking in bell diameter from about 4.0 mm to 3.8 mm by day 14, but remained in apparent good condition. Ephyrae reared at 22.5°C and above everted their bells, were in poor condition, and were unable to feed or swim effectively by about day ten. In this study the optimal temperature range for rearing A. labiata ephyrae was 12°C—21°C, which corresponds with the reported range for this species.
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=315043
JELLYFISH LIFE CYCLE
VIEWS OF JELLYFISH
1 comment:
You are aware that the Portugese man-of-war is not a true jellyfish? It's from the class hydrozoa (not scyphozoa), and is a colony of hydoirds.
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