Life in the Deep, Dark Sea

Science · Ocean Life · ages 9-11

Name ______________________ Date ____________

The giant squid lives in total darkness, and its eyes are as wide as dinner plates. What do those huge eyes help it do?
- Make its own light, like a lamp
- Look scary to other animals
- Catch every tiny bit of light so it can see in the dark
What does it mean when a deep-sea animal is bioluminescent?
- It can change its color to hide
- It can produce its own light
- It can breathe out of water
Hydrothermal vents can support life even though no sunlight reaches them.
Circle one: True False
An anglerfish dangles a glowing lure in front of its mouth to attract prey. What is this an example of?
- Camouflage
- Migration
- Bioluminescence
Deep-sea animals live where the water pressure is crushing. Which body feature helps them survive this?
- Thick hard shells like a turtle
- Soft, flexible bodies without big air spaces
- Large lungs full of air
At a hydrothermal vent, where does the energy that feeds the whole community first come from?
- Sunlight shining down from the surface
- Chemicals in the hot vent water
- Food falling from ships above
If a hydrothermal vent stopped releasing its chemical-rich water, what would most likely happen to the animal community living there?
- It would switch to using sunlight instead
- It would stay exactly the same
- It would go hungry and struggle
A classmate says deep-sea fish must have thin, weak bodies since it's so cold and dark down there. What's the mistake?
- Deep-sea fish don't have bodies at all
- Built to handle crushing pressure
- There is no water pressure in the deep sea

Answer key

For grown-ups. Fold this page away before handing over the rest.

Life in the Deep, Dark Sea W1-mt_dRCnJEIwk4-s1

Catch every tiny bit of light so it can see in the dark · In total darkness, huge eyes gather as much of the faint glow as possible, which helps the squid see.
It can produce its own light · Bioluminescent animals make light inside their own bodies using a chemical reaction.
True · Bacteria near the vents turn chemicals from the hot water into food energy, so sunlight isn't needed.
Bioluminescence · The anglerfish makes its own light, which is exactly what bioluminescence means.
Soft, flexible bodies without big air spaces · Air-filled spaces would get crushed under pressure, so many deep-sea animals have soft bodies with little or no trapped air.
Chemicals in the hot vent water · Special bacteria use chemicals from the vent water to make food energy, starting the whole food chain there.
It would go hungry and struggle · The vent bacteria need those chemicals to make food. Without them, the energy source that feeds the whole community disappears.
Built to handle crushing pressure · Pressure, not just cold or darkness, is the biggest challenge, and deep-sea animals have adaptations like flexible bodies to handle it.