Question

1. meet the cambrian critters

a) how long ago was the cambrian period?
b) what is the \cambrian explosion\

1. sanctacaris

a) nickname
b) is it part of the arthropod lineage?
c) sanctacaris added as a branch to what part of the tree

1. opabinia

a) how did it acquire food?
b) is it part of the arthropod lineage?
c) opabinia lacks what namesake trait of arthropods?

1. pikaia

a) is it part of the arthropod lineage?
b) pikaia was probably what type of animal?

1. hallucigenia

a) is it part of the arthropod lineage?
b) hallucigenia added as a branch to what part of the tree

1. naraoia

a) is it part of the arthropod lineage?
b naraoia added as a branch to what part of the tree
21.tools for success - crustaceans: living toolboxes. for each tool, name the arthropod that has a similar appendage.
crowbar
paddle
broom
leaf blower
clamp
sledgehammer

1. arthropod adaptability - describe two ways the legs of arthropods are adapted for different purposes.
2. sidetrip: extreme adaptations: eating with your feet. sketch the head of an insect and label the mouthparts

Explanation:

a) The Cambrian period occurred about 541 million years ago. The "Cambrian Explosion" refers to a relatively short - time interval in the Cambrian when there was a rapid diversification of life forms.
b) Sanctacaris is sometimes called the "Ur - arthropod". It is part of the arthropod lineage and was added as a branch near the base of the arthropod tree.
c) Opabinia acquired food using its long, flexible proboscis. It is not part of the arthropod lineage and lacks jointed appendages which are a key trait of arthropods.
d) Pikaia is not part of the arthropod lineage and was probably a primitive chordate.
e) Hallucigenia is not part of the arthropod lineage and was added as a branch in the stem - group of the Lophotrochozoa or other non - arthropod groups.
f) Naraoia is part of the arthropod lineage and was added as a branch within the arthropod tree.
g) For the tools: Crowbar - crayfish (large claws can be used to pry); Paddle - shrimp (swimming appendages); Broom - some crustaceans with setae for filtering food; Leaf blower - not a direct match but some crustaceans can move water with appendages; Clamp - crabs (claws for grasping); Sledgehammer - some large - clawed crustaceans for breaking.
h) Arthropod legs can be adapted for walking (e.g., long, slender legs in insects for moving on land), and for grasping (e.g., the pincers of crabs for catching prey).
i) For sketching the insect head, it typically has compound eyes, antennae, and mouthparts like mandibles, maxillae, and labium.

Answer:

1. a) About 541 million years ago.

b) A rapid diversification of life forms in the Cambrian.

1. a) "Ur - arthropod".

b) Yes.
c) Near the base of the arthropod tree.

1. a) Using its long, flexible proboscis.

b) No.
c) Jointed appendages.

1. a) No.

b) A primitive chordate.

1. a) No.

b) In the stem - group of the Lophotrochozoa or other non - arthropod groups.

1. a) Yes.

b) Within the arthropod tree.

1. Crowbar - crayfish; Paddle - shrimp; Broom - crustaceans with setae; Leaf blower - no direct match; Clamp - crabs; Sledgehammer - large - clawed crustaceans.
2. For walking and for grasping.
3. Sketch should include compound eyes, antennae, mandibles, maxillae, labium.