Muir Woods Nature Detectives



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Crustacean Frustration

How does competition affect the food chain?

1. Learn about all the different plants and animals in 2 creek locations.

2. After exploration, compare what animals are eaten at each creek location.

3. Answer the on-screen questions about crayfish removal.

To learn more about the plants and animals, click through to their descriptions in your notebook.

Location #1

Redwood Creek runs through this part of the forest. Its clear water runs over a rocky bed to deeper pools. Listen to the sound of the creek by using the player here, or on a new page.

In each of the 4 pools of water in this part of the creek there are five salmon smolt swimming. Standing motionless in one pool is a hungry snowy egret. Splashing in and out of the water in another pool a sleek river otter is hunting. Near the water in the creek bed a banana slug crawls. A giant Pacific salamander hides in the shade under a log.

The snowy egret has eaten four of the five salmon smolt in the pool. The river otter has eaten four salmon smolt from its pool. Twenty smolts were in this part of the creek, but now twelve are left to swim to sea.

PIcture of the forest in location one with the plants and animals in it.

See a zoomed in view of this picture of location 1 in a new window. Or, see a panorama of location 1 in a new window (requires Flash).

Location #2

In another part of Redwood creek are four other deep pools of water, each with five salmon smolts. However, also living in each pool of water lives a non-native crayfish. In one deep pool a snowy egret hunts for salmon or crayfish to eat. In another pool is a hungry river otter looking for small salmon and crayfish. Near the creek scampers a small dusky-footed wood rat. On a tree’s branch above the water sits a barred owl, which is looking for crayfish or dusky-footed wood rats to eat.

In the first pool, the river otter ate four fish and the crayfish ate one smolt. The crayfish was still hungry and moved to another pool to keep hunting. In the second pool the crayfish ate two smolts and the snowy egret ate three smolts. The egret was still hungry and moved on to another pool to keep hunting. In the third pool, the crayfish ate two smolts. But then the barred owl ate the crayfish and the dusky-footed wood rat. In the fourth pool, there are now two crayfish and the egret hunting for smolts. A crayfish ate two smolts. Then the hungry snowy egret ate one smolt and the other crayfish ate two smolts. There were twenty smolts in this part of the creek, but now there are only three left to swim out to sea.

PIcture of the forest in location two with the plants and animals in it.

See a zoomed in view of this picture of location 2 in a new window. Or, see a panorama of location 2 in a new window (requires Flash).

Please answer the questions below.