Benthos

Question 1

Dreissena Polymorpha

Answer 1

1. Common name: zebra muscles
2. Benthos
3. Native to Eurasia, but invasive in the Great Lakes region
4. Effective filter feeders - remove nutrients as well as small algae and zooplankton from water column and can cause oligotrophication and profound alterations to nutrient cycling
5. Colonize rapidly because they can attach to a wide array of substrates, including water supply pipes which can have large economic costs

Question 2

Trichoptera (larvae)

Answer 2

1. Common name: caddisfly
2. Benthos
3. Caddisfly adults are terrestrial and larvae are aquatic. The larvae make protective cases made of silk which may be reinforced with other materials including leaves, sand, twigs, etc.
4. Sensitive to pollution so their presence is associated with good water quality (“EPT” taxa)

Question 3

Chaoborid (larvae)

Answer 3

1. Common name: glassworm or phantom midge (Diptera)
2. Benthos
3. Terrestrial adults and aquatic larvae
4. Transparent body allows avoidance of visual predators
5. Predatory adaptations:
   a) Raptorial antennae to grasp prey and bring to mouth
   b) Diel vertical migration - follow zooplankton prey in water column

Question 4

Anisoptera (nymph)

Answer 4

1. Common name: dragonfly
2. Benthos
3. Terrestrial adults and aquatic nymphs are both predatory; prey can include larvae, tadpoles, and even small fish

Question 5

Benthic Organisms

Answer 5

1. Living on, near or in the sediments
2. Zoobenthos can be divided into two groups:
   a) Insects - process detritus in lakes and streams,
   b) All the other invertebrates - divided into 3 Phyla: Crustacea, Mollusca, and Annelida

Question 6

Crustacea

Answer 6

1. Zoobenthos invertebrate phyla
2. Anthropods
3. Distinctive because of their 2 pairs of antennae and
   anterior body segments bearing paired, jointed biramous appendages

Question 7

Mollusca

Answer 7

1. Zoobenthos invertebrate phyla
2. Characterized by a body enclosed in a hard shell and divided into two
   classes:
   a) Pelecypods - two halves of shell attached dorsally, e.g. clams
   b) Gastropods - spiral or discoidal coiled shell, e.g. snails