There are about 200 species of jellyfish. Most look like floating umbrellas. Their body is shaped like a bell. Their tentacles hang beneath.

One of the biggest jellyfish is the lion's mane. It lives in the Arctic, northern Pacific and northern Atlantic. Its body is 2.3 metres across and its tentacles are 36.5 metres long. If it stood up on its tentacles, it could look into the window of a 12th-storey apartment!

One of the smallest jellyfish is the Irukandji (eer-uh-CON-jee), from Australia. It is just 1cm long.

Jellyfish can be dangerous because their tentacles are covered in stinging cells. These can stun and kill shrimps, fish and other ocean animals.

Sea wasp jellyfish that live in Japanese and Australian seas are so poisonous that they can kill a human being in a few minutes.

If you see a jellyfish, in the water or on the beach, don't touch it!

True or false?

1 There are about 2,000 types of jellyfish.

2 Jellyfish don't have a skeleton.

3 Jellyfish kill their prey by stinging it.

Starfish

Find words that mean:

nuisance, but not, dividing, spine

Starfish live in oceans all over the world except the North and South Pole. Although they are called starfish, these animals aren't fish. Fish have a backbone but starfish don't.

Scientists have named 1,800 starfish species but they keep finding new ones. Nobody really knows how many species there are.

Starfish come in all sorts of colours: blue, red, brown, yellow, white, purple and black. Many starfish have five arms. But some have more: the sea lily starfish has 200 arms.

Starfish eat clams, oysters and snails. Some eat coral. The crown-of-thorns starfish is a famous pest that destroys coral reefs.

Starfish can do some weird things. Some can regrow an arm if they lose one. Some can reproduce by splitting their body in half. Some can push their stomach out through their mouth and digest their food outside their body.

Frilled shark

Choose the correct alternative:

The frilled shark lives in oceans all over the world. This carnivore/herbivore can grow up to 2 metres long. It eats squid, fish and other sharks. Because it lives more than 1km under the surface, scientists don't know much about it.

This shark first appeared about 200 million years ago. Because it hasn't changed much, it's called a living/dead fossil.

The frilled shark is different in many ways from modern sharks. The frilled shark looks more like an eel than a shark. The frilled shark has a blunt face. The modern shark has a pointed face. The frilled shark has its mouth and nose at the back/front of its body. The modern shark has them below.

But the strangest thing may be their fast/slow reproduction rate. Scientists think that frilled shark pregnancies last two or even three years.

Nudibranchs

Find the correct antonyms, or words that mean the opposite, of:

vegetarians, old, delicious, dull

Nudibranchs (noo-dee-branks) live in oceans all over the world. Scientists have named more than 3,000 different species - and they keep finding new ones.

Nudibranchs have soft bodies. Because of this, some people call them sea slugs.

Nudibranchs come in lots of colours and sizes. The bright orange Hexabranchus from Hawaii can grow to 60cm long. The mauve jorunna from Australia is less than 2cm long.

All these little animals are carnivores. They eat sea anemones, sponges, barnacles and other sea slugs.

Scientists aren't sure what animals eat sea slugs. But we do know they have good defences. Nudibranchs can sweat out a nasty-tasting slime. Some are also poisonous.

Sea slugs may look soft but they're tough little creatures.

See starfish and nudibranchs in Hong Kong

There are about 21 different starfish living in Hong Kong waters. Scientists have also found 230 nudibranch species in Hong Kong. At least five of these are new to science.

To see starfish and nudibranchs, check out Shek Ngau Chau or Breaker Reef. The coral reefs in front of the lighthouse at Port Island is also a good spot. Alternatively, check out the parks, such as Hoi Ha Wan Marine Park and Tung Ping Chau Marine Park.

Alternatively, go to the nearest rocky shore and check rock pools at low tide when you are walking along the beach. If you are snorkelling, look for blue and yellow striped nudibranchs looking out from under rocks and stones. Also look for bright orange nudibranchs with a blue and white striped fringe, eating sponges.

fab fact!

Irukandji jellyfish are just 1cm long, but they have a very poisonous sting. Some people who are stung feel so bad that they ask their doctors to kill them.

fab fact!

The first frilled sharks appeared 200 million years ago. Two other living fossils from that time are the gingko tree and the tuatara, a lizard-like reptile.

compare!

The world's smallest starfish is the Australian paddle-spined sea star. It has five arms. Its body is 5mm across. One of the biggest is the sunflower sea star. It has 15 to 26 arms. Its body is more than 1m across.

now do this

Answer the following questions. To test your memory, try answering without referring to the text. If you can't remember the details, read the piece again.

1 Jellyfish have bodies made up mostly of ...

a. blood

b. poison

c. water

2 One of the world's biggest jellyfish is the ...

a. sea wasp

b. lion's mane

c. Irukandji

3 Starfish eat ...

a. algae and plants

b. anemones, sponges and barnacles

c. clams, oysters and snails

4 Nudibranchs eat ...

a. algae and plants

b. anemones, sponges and barnacles

c. clams, oysters and snails

5 Frilled sharks live ...

a. in shallow coastal waters

b. only in the Arctic ocean

c. deep in the ocean

Look online for more about sea life

Enchanted Learning Oceans

Learn where the major oceans and seas are, and click on the links to find fact sheets about ocean animals.

AFCD Hong Kong Marine Life

Check out quick facts and lots of pictures of our own marine treasures. Click on the links in these articles for more information. Great for homework projects.

Marine Life

Explore videos and articles about hundreds of plants and animals that live in oceans around the world.

Sea Slug Forum

Click on any species name to see amazing pictures and short descriptions of nudibranchs from all over the world.

Nat Geo Wild

You can learn more about jellyfish in Jellyfish Invasion on Nat Geo Wild on Friday at 6pm and Saturday at 12pm.

Answers:

June 10

Myths and legends: 1. F, 2. T, 3. T

The dugong: shallow, attacked, slowly, fierce

Amazon River dolphin: yummy, live, hunt, watch

Walrus: float, weigh, pull, slip

Quiz: 1. a, 2. c, 3. b, 4. b, 5. a, 6. b