Q 01/05

The rainbow colours that ripple along a comb jelly's sides when it swims are produced by what?

A) Bioluminescence

B) Scattered light

C) Coloured pigments

D) Symbiotic algae

Answer · why

B) Scattered light

Scattered light makes the rainbow: the tightly packed hairs of each beating comb plate break it into shifting colours, much as an oil slick does. The ...

Q 02/05

Instead of a jellyfish's stinging cells, a comb jelly's tentacles carry cells that release what?

A) Venom

B) Acid

C) Glue

D) Slime

Answer · why

C) Glue

Glue bursts from cells called colloblasts when prey touches a tentacle, so comb jellies cannot sting swimmers. One genus, Haeckelia, cheats by reusing...

Q 03/05

Comb jellies have no brain, so which simpler system under the skin coordinates their swimming?

A) A nerve net

B) A spinal cord

C) Twin nerve cords

D) A neural tube

Answer · why

A) A nerve net

A nerve net runs beneath the skin, densest around the mouth, tentacles and comb rows. Many of its nerve cells merge into one continuous web, a wiring ...

Q 04/05

Which sea's fisheries crashed in the 1980s after the sea walnut, an American comb jelly, invaded?

A) Red Sea

B) Yellow Sea

C) Coral Sea

D) Black Sea

Answer · why

D) Black Sea

The Black Sea had nothing that ate the newcomer, and by 1989 it held up to 400 sea walnuts per cubic metre, all feeding on plankton and fish eggs.

Q 05/05

In laboratory experiments, what can two injured sea walnuts do, even if genetically different?

A) Fuse into one animal

B) Devour one another

C) Swap healthy tentacles

D) Spawn at the same time

Answer · why

A) Fuse into one animal

Two sea walnuts can fuse into one animal, joining even their nervous and digestive systems. Within about two hours, nearly all of the merged body's mu...