Choose the correct letter.

1. Many shorebirds feed on the mudflats of estuaries. When would be the best time for the birds to catch stranded fish and vertebrates?
a. daytime
b. high tide
c. low tide
d. sunrise

2. The blue crab is one of the fastest swimming crabs in the world. Which is an adaptation of the crab for this?
a. body shape
b. jointed legs
c. large claws
d. paddle-like rear feet

3. In many desert regions where water is diverted from streams and rivers to people in cities, animals tend to ____.
a. stop to search for food and water.
b. migrate to tropical rainforest.
c. move closer to cities to get food.
d. become more active in daylight hours.

4. If the plankton are removed from the estuary, what may happen to the estuarine food web?
a. Planktons are producers so their removal may not have an effect.
b. The other animals in the estuary will have to find other food sources.
c. Removal of any organism like the plankton will greatly affect the ecosystem.
d. Filter feeders like oysters and clams will not be affected on the presence of plankton.

5. Why do plants found in estuaries need to adapt to salty conditions?
a. Plants need to taste salty.
b. These plants feed on salt.
c. Salt dominates in estuaries.
d. Strong currents make them healthy.