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Brownies support whales and dolphins

Who Eats What?

Moonlight the bottlenose dolphin eating a salmonA food chain is a simple model for who eats what. e.g.

Killer Whale (Orca) – eats- Seals – eats- squid - eats- krill- eats- phytoplankton.
A food pyramid would also show which members of the food chain exist more numerously than others.

Did you know?!
If whales are washed up on the beach, they may have suffered so much contamination with poisonous material that they must be decontaminated as hazardous waste. The pollutants accumulate on every step of the food chain and gather in the blubber of whales.

Click here to download a food chain mobile to colour in and create.


Interesting Info!

Some whales, such as the blue whale, don’t have teeth, but instead have baleen (comb-like bristles that hang from the upper jaws of most of the largest whales). These animals feed by filtering (sieving) plankton (tiny drifting animals and plant-like organisms that live in the ocean) from the water.

Other cetaceans (whales and dolphins) have teeth and feed on larger animals such as fish. All dolphins have teeth rather than baleen. Orcas, sometimes called killer whales, are actually the largest member of the dolphin family and therefore have teeth and feed on fish and other big prey.


baleen and teeth animation


Feeding Frenzy
- experiment to discover how different whales feed
!

What you’ll need:

* Plastic tank (fish tank or similar)
* 2 plastic trays
* Towels
* Laminated drawings of fish
* Lentils/pulses/rice as plankton
* Small sieve
* 2 small garden sticks (about 1.5 times as high as the tank)
* Paperclips
* Waterproof glue or tape
* Laminated picture or drawing of an orca
* Laminated picture or drawing of a blue whale
* Laminated drawings of fish (about 10)

Preparation

1. Attach a paperclip to the end of one stick and the laminated orca picture to the other end
2. Attach the small sieve to one end of the other stick and the laminated blue whale picture to the other end of this stick
3. Attach bent paper clips to the laminated fish to act as hooks
4. Fill the tank with water, add the fish and plenty of plankton
5.Place the 2 trays a short distance away and label one ‘blue whalestomach’ and the other ‘orca stomach’. The area around the tank willget wet so cover with towels if needed

Time to experiment!

1. Try being a blue whale and catching the plankton with the sieve
2. When you have caught some, transfer it to the blue whale stomach tray and then catch some more from the tank etc
3. Now try being an orca and catching fish.
4. When you have caught a fish, transfer it to the orca stomach tray and try to catch another one

Why don’t you time yourself trying both feeding methods and see which one takes longer?

You should find that the plankton is easy to catch but to fill up a whale you have to catch a lot of it. The fish are much harder to catch but the orca needs less of them to fill it up.