Jellyfish

Answer 1

NO

Jellyfish live mainly in the ocean, but they aren’t actually fish – they’re plankton. These plants and animals either float in the water or possess such limited swimming powers that currents control their horizontal movements. Some plankton are microscopic, single-celled organisms, while others are several feet long. Jellyfish can range in size from less than an inch to nearly 7 feet long, with tentacles up to 100 feet long.

Question 2

Answer 2

Box Jelly

(class Cubozoa)

Box jellyfish (class Cubozoa) are cnidarian invertebrates distinguished by their cube-shaped medusae. Box jellyfish are known for the extremely potent venom produced by some species: Chironex fleckeri, Carukia barnesi and Malo kingi are among the most venomous creatures in the world. Stings from these and a few other species in the class are extremely painful and sometimes fatal to humans. The most dangerous species are limited to tropical indo-pacific regions (e.g. Australia). Other less hazardous species are found elsewhere including California.

Question 3

Answer 3

Sea gooseberry

(Pleurobrachia bachei)

These comb jellies (in the phylum Ctenophora) are often mistaken for medusoid Cnidaria, but are not dangerous to handle. The sea gooseberry is relatively short-lived, only alive for around 4–6 months. P. bachei is found along the West coast of North America from Southeast Alaska to Mexico. An individual sea gooseberry’s body length can reach up to 20 mm (0.79 in) with each of the two tentacles stretching 150 mm (5.9 in).

Answer 4

Jellyfish are also members of the phylum Cnidaria, (from the Greek word for “stinging nettle”) and the class Scyphozoa (from the Greek word for “cup,” referring to the jellyfish’s body shape). All cnidarians have a mouth in the center of their bodies, surrounded by tentacles. The jellyfish’s cnidarian relatives include corals, sea anemones and the Portuguese man-o’-war.

Question 5

Answer 5

A jellyfish’s body generally comprises six basic parts:

• The epidermis, which protects the inner organs
• The gastrodermis, which is the inner layer
• The mesoglea, or middle jelly, between the epidermis and gastrodermis
• The gastrovascular cavity, which functions as a gullet, stomach, and intestine all in one
• An orifice that functions as both the mouth and anus
• Tentacles that line the edge of the body

Answer 6

An adult jellyfish is a medusa (plural: medusae), named after Medusa, the mythological creature with snakes for hair who could turn humans to stone with a glance.

Answer 7

1. Liberally wash the area with vinegar for 30 seconds or more to deactivate the stinging cells.
2. Immerse in hot water for 20 minutes to treat the pain.

Answer 8

Some jellyfish also have ocelli: light-sensitive organs that do not form images but which can detect light, and are used to determine up from down, responding to sunlight shining on the water’s surface. These are generally pigment spot ocelli, which have some cells (not all) pigmented.
Certain species of jellyfish, such as the Box jellyfish, have been revealed to be more advanced than their counterparts. The Box jellyfish has 24 eyes, two of which are capable of seeing color, and four parallel brains that act in competition, supposedly making it one of the only creatures to have a 360 degree view of its environment. It is suggested that the two eyes that contain cornea and retina are attached to a central nervous system which enables the four brains to process images. It is unknown how this works, as the creature has a unique central nervous system

Question 9

Answer 9

Crown jellyfish

(Cephea cephea)

Width to 40 cm. Pink to lilac above, brown below, with a central dome covered in 10-50 large, irregular protuberances and circled by a shallow “moat”. Mouth-arms recurved, with many filaments, just exceeding disc width. Habitat: oceanic, occasionally drifting inshore. Distribution: tropical Indo-Pacific, N. Australia, some records W Africa.

Answer 11

Most jellyfish are dioecious, meaning that individuals are either male or female, but some species are
hermaphrodite (having both male and female gonads)

Question 12

Answer 12

Upside-down jelly

(Cassiopea sp)

Cassiopea is a genus of scyphozoan jellyfish very commonly found in shallow mangrove swamps, mudflats, and turtle grass flats in Florida and various other similar environments around the world, where it lives usually upside-down on the bottom. The photosynthesis occurs because, like coral, they host zooxanthellae in their tissues. The stinging cells are excreted in a mucus; swimming over these jellies (especially using swim fins) may cause transparent, essentially invisible, sheets of this mucus to be lifted up into the water column, where they are then encountered by unsuspecting swimmers. The stings, appearing in the form of a red rash-like skin irritation, are notorious for being extraordinarily itchy.

Question 13

Answer 13

Pacific Sea nettle

(Chrysaora fuscescens)

Sea nettles have a distinctive golden-brown bell with a reddish tint. The bell can grow to be larger than one meter (three feet) in diameter in the wild, though most are less than 50 cm across. The long, spiraling, white oral arms and the 24 undulating maroon tentacles may trail behind as far as 3.6 to 4.6m (12 to 15 feet). For humans, its sting is often irritating, but rarely dangerous. They are commonly found along the coasts of California and Oregon (amoung other areas).

Question 14

Answer 14

Bubber Jelly

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The most commonly encountered jellyfish along the Australian eastern coast and large swarms sometimes appear in estuarine waters. In Sydney waters, the Jelly Blubber’s large bell is a creamy white or brown colour, but farther north it is usually blue. This is because the jellyfish has developed a symbiotic relationship with algal plant cells that are kept inside its body. These plants vary in colour from region to region. The algae photosynthesise, converting sunlight into energy that can be used by the jellyfish. Its bell pulses in a distinctive, staccatolike rhythm. There is no obvious mouth on the underside, but there are small openings on each arm, through which food is passed to the stomach.

Question 15

Answer 15

Spotted Jelly

(Mastigias papua)

The spotted jelly or lagoon jelly is a species of jellyfish. It lives mainly in the southern Pacific Ocean. Instead of one single mouth, they appear to have several smaller mouth openings in their oral arms. These feed on zooplankton.
In Japan—especially along Pacific coast areas—these are sold as novelty pets, along with photoautotrophic phytoplankton, and are called takokurage, or “octopod” or “rammer” jellies. They seem to have a lifespan of approximately 4 months and are active primarily in mid-summer to early-fall.

Answer 16

Jellyfish are about 98 percent water. If a jellyfish washes up on the beach, it will mostly disappear as the water evaporates

Question 17

Answer 17

Purple-striped Jellyfish

(Chrysaora colorata)

The purple-striped jelly is a species of jellyfish that exists primarily off the coast of California in Monterey Bay. The bell (body) of the jellyfish is up to 70 cm (27.6 inches or 2.3 feet) in diameter, typically with a radial pattern of stripes. The tentacles vary with the age of the individual, consisting typically of eight marginal long dark arms, and four central frilly oral arms. It is closely studied by scientists due to not much being known about their eating habits.

Question 18

Answer 18

Lion’s Mane Jelly

(Cyanea capillata)

The lion’s mane jellyfish is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans The largest recorded specimen found, washed up on the shore of Massachusetts Bay in 1870, had a bell (body) with a diameter of 7 feet 6 inches (2.29 m) and tentacles 120 feet (37 m) long. That specimen was longer than a blue whale and is considered one of the longest known animals in the world.

Answer 19

Jellyfish lifespans typically range from a few hours (in the case of some very small hydromedusae) to several months. Life span and maximum size varies by species. Jellyfish held in public aquariums are carefully tended, fed daily even when food might be seasonally rare in the wild, and sometimes treated with antibiotics if they develop infections, so may live several years, though this would be very unusual in the sea. Most large coastal jellyfish live 2 to 6 months.

Answer 20

Crystal Jelly

(Aequorea sp)

A bioluminescent hydrozoan jellyfish, or hydromedusa, that is found off the west coast of North America. Almost entirely transparent and colorless. The bell margin is surrounded by uneven tentacles, up to 150 of them in fully-grown specimens. The tentacles possess nematocysts that aid in prey capture, although they have no effect on humans. Specimens larger than 3 cm usually possess gonads for sexual reproduction, which run most of the length of the radial canals and are visible in the photos in this article as whitish thickenings along the radial canals. They are found along the North American west coast of the Pacific ocean from the Bering Sea to southern California.

Question 21

Answer 21

Elegant Jellyfish

(Tima sp)

Tima formosa is a colonial species of marine hydrozoa in the family Conica. They live in northern parts of the Atlantic Ocean, in the upper epipelagic zone.

Question 22

Answer 22

After the male releases its sperm through its orifice into the water, the sperm swim into the female’s orifice and fertilize the eggs. Several dozen jellyfish larvae can hatch at once. They eventually float out on the currents and look for a solid surface on which to attach, such as a rock. When they attach they become polyps – hollow cylinders with a mouth and tentacles at the top. The polyps later bud into young jellyfish called ephyrae. After a few weeks, the jellyfish float away and grow into mature medusae. A medusa can live for about three to six months.

Question 23

Answer 23

Moon Jelly

(Aurelia aurita)

The medusa is translucent, usually about 25–40 cm in diameter, and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell. It feeds by collecting medusae, plankton and mollusks with its tentacles, and bringing them into its body for digestion. It is capable of only limited motion, and drifts with the current, even when swimming.

Answer 24

An Australian box jellyfish called the sea wasp can kill a grown man in a matter of seconds or minutes. Because the harpoons are so shallow, however, Australians have learned that they can protect themselves while swimming in sea wasp waters simply by covering their exposed skin with pantyhose.

Answer 25

Asexual reproduction by division into body segments, as in tapeworms and jellyfish.

In jellyfish the scyphistomea starts to split up into a stack of discs, rather like a stack of plates, a process called strobilation. This stack of disks is called a strobila. One by one each disc detaches from the end of the strobila and become a tiny jellyfish, slightly different from the mature form, and called an ephyra. Each ephyra is only a few millimetres in diameter, but will feed and grow, and if it survives then it will become a mature jellyfish

Answer 26

Jellies are carnivorous, feeding on plankton, crustaceans, fish eggs, small fish and other jellyfish, ingesting and voiding through the same hole in the middle of the bell. Jellies hunt passively using their tentacles as drift nets.