Anchor Papers ~ Biology ~ Item 22


	Item 22 Anchor Papers

A population of sea urchins in a kelp forest ecosystem is being overfished. A team of students believe that a decline in the number of sea urchins will affect the organisms in the kelp forest ecosystem. The kelp forest food web below shows the relationships among the organisms in the kelp forest ecosystem.

The students believe that the kelp crab population will decrease if the sea urchin population decreases. Use the kelp forest food web to support or refute the students’ conclusion. In your response, be sure to

describe the roles of the kelp crab, sea otter, and sea urchin in the food web
describe the relationships between the kelp crab, sea otter, and sea urchin
explain how each organism in the food web would be affected by a change in the sea urchin population

Write your answer in your Answer Book.

Score Level 1 Anchor Paper
This response shows some understanding of the question. The ecological relationships among the otter, crab, and urchin are addressed in a very general manner (kelp crabs and sea urchins feed off of kelp, only to be eaten by the sea otter). In a further explanation, the student overstates the effect of a decrease in the populations of the organisms. (The sea urchin and crab won't get the food from the kelp and die off. The otter will starve and die off too.) The supporting details are minimally effective.
Score Level 1 Anchor Paper
This response shows some understanding of the question. The student correctly identifies an ecological role (consumers) and a few ecological relationships (sea otters eat kelp crabs; kelp crabs eat kelp). However, in stating that a sea urchin decline will not affect the kelp crab population, the response demonstrates a major misconception about the interdependency among organisms in a food web. The supporting details are minimally effective.
Score Level 2 Anchor Paper
This response shows a basic understanding of the question. Adequate supporting details are provided. The student identifies the correct ecological roles of the crab, the otter, and the urchin (consumers). The ecological relationships among the crab, urchin, and otter (crab and sea urchin both eat kelp and are both eaten by sea otters) are briefly mentioned. An explanation of how the food web is affected by a change in the sea urchin population is brief, but accurate (sharks and sea otters would be less; more kelp and more kelp crabs; Elephant seals [decrease]).
Score Level 2 Anchor Paper
This response shows a basic understanding of the question. The correct ecological role of the otter is given (consumer), and the ecological relationships among the otters, crabs, and urchins are addressed (sea otters eat the sea urchins and the kelp crab). Adequate supporting details are used to explain the effects of the sea urchin decline (The sea otter population would decrease at first; kelp population will increase; kelp crab population to increase; sea otter population to increase again; horn shark population would decrease; Northern Elephant Seal population would decrease).
Score Level 3 Anchor Paper
This response demonstrates a good understanding of the question. Synthesis of information is evident throughout the description of the effects on the sea otter and kelp crab (The sea otters wouldn't be able to eat urchins as much and would rely mostly on kelp crab. This would level out the kelp crab population to about where it was before). A description of how seals and sharks would be affected is provided (The horn sharks and the Northern elephant seals populations would decrease for awhile then level back out). The supporting details are generally complete, and the use of scientific terminology ([first order] consumer; [second order] consumer) strengthens the response.
Score Level 3 Anchor Paper
This response demonstrates a good understanding of the question. Using appropriate scientific terminology (predator; prey), the student describes the ecological relationships among the otter, crab, and sea urchin (kelp crab and sea urchin get eaten by the sea otters). The effects of the sea urchin decline on the other organisms are explained using generally complete supporting details (if sea urchins disappeared … the horn sharks wouldn't have anything to eat and without sharks the seals don't eat; the crabs will experience slight increase because of abundance in kelp, but then will decrease substantially because of sea otters having no other food).
Score Level 4 Anchor Paper
This response shows a full and complete understanding of the question. Using pertinent and complete supporting details, the student thoroughly addresses the ecological roles and accurately describes the relationships between the otter and the crab, and the otter and the urchin. The effects of the sea urchin decline are also fully explained (kelp population would increase, leaving the kelp crab population to also increase, but the sea otter population might decrease; the horn shark population would greatly decrease and so would the elephant seal since their main food source would be decreasing). The accurate use of scientific terminology ([primary] consumer; herbivore; [secondary] consumer; predator; prey; carnivore) enhances the response.
Score Level 4 Anchor Paper
This response shows a full and complete understanding of the question. The ecological role of every organism is integrated into the description of the effects of an urchin decline (an increase of the kelp population because it lost a predator; kelp crab would diminish because the sea otters would prey on them more often after losing a food source, and the sea otter population would also decrease in time). The supporting details are pertinent and complete, and the use of accurate scientific terminology ([first degree] consumer; herbivore; [second degree) consumer; carnivore; predator; prey) enhances the response.

Anchor Papers ~ Biology ~ Item 22

describe the roles of the kelp crab, sea otter, and sea urchin in the food web
describe the relationships between the kelp crab, sea otter, and sea urchin
explain how each organism in the food web would be affected by a change in the sea urchin population

Write your answer in your Answer Book.

Score Level 1 Anchor Paper

This response shows some understanding of the question. The ecological relationships among the otter, crab, and urchin are addressed in a very general manner (kelp crabs and sea urchins feed off of kelp, only to be eaten by the sea otter). In a further explanation, the student overstates the effect of a decrease in the populations of the organisms. (The sea urchin and crab won't get the food from the kelp and die off. The otter will starve and die off too.) The supporting details are minimally effective.

Score Level 1 Anchor Paper

This response shows some understanding of the question. The student correctly identifies an ecological role (consumers) and a few ecological relationships (sea otters eat kelp crabs; kelp crabs eat kelp). However, in stating that a sea urchin decline will not affect the kelp crab population, the response demonstrates a major misconception about the interdependency among organisms in a food web. The supporting details are minimally effective.

Score Level 2 Anchor Paper

This response shows a basic understanding of the question. Adequate supporting details are provided. The student identifies the correct ecological roles of the crab, the otter, and the urchin (consumers). The ecological relationships among the crab, urchin, and otter (crab and sea urchin both eat kelp and are both eaten by sea otters) are briefly mentioned. An explanation of how the food web is affected by a change in the sea urchin population is brief, but accurate (sharks and sea otters would be less; more kelp and more kelp crabs; Elephant seals [decrease]).

Score Level 2 Anchor Paper

This response shows a basic understanding of the question. The correct ecological role of the otter is given (consumer), and the ecological relationships among the otters, crabs, and urchins are addressed (sea otters eat the sea urchins and the kelp crab). Adequate supporting details are used to explain the effects of the sea urchin decline (The sea otter population would decrease at first; kelp population will increase; kelp crab population to increase; sea otter population to increase again; horn shark population would decrease; Northern Elephant Seal population would decrease).

Score Level 3 Anchor Paper

This response demonstrates a good understanding of the question. Synthesis of information is evident throughout the description of the effects on the sea otter and kelp crab (The sea otters wouldn't be able to eat urchins as much and would rely mostly on kelp crab. This would level out the kelp crab population to about where it was before). A description of how seals and sharks would be affected is provided (The horn sharks and the Northern elephant seals populations would decrease for awhile then level back out). The supporting details are generally complete, and the use of scientific terminology ([first order] consumer; [second order] consumer) strengthens the response.

Score Level 3 Anchor Paper

This response demonstrates a good understanding of the question. Using appropriate scientific terminology (predator; prey), the student describes the ecological relationships among the otter, crab, and sea urchin (kelp crab and sea urchin get eaten by the sea otters). The effects of the sea urchin decline on the other organisms are explained using generally complete supporting details (if sea urchins disappeared … the horn sharks wouldn't have anything to eat and without sharks the seals don't eat; the crabs will experience slight increase because of abundance in kelp, but then will decrease substantially because of sea otters having no other food).

Score Level 4 Anchor Paper

This response shows a full and complete understanding of the question. Using pertinent and complete supporting details, the student thoroughly addresses the ecological roles and accurately describes the relationships between the otter and the crab, and the otter and the urchin. The effects of the sea urchin decline are also fully explained (kelp population would increase, leaving the kelp crab population to also increase, but the sea otter population might decrease; the horn shark population would greatly decrease and so would the elephant seal since their main food source would be decreasing). The accurate use of scientific terminology ([primary] consumer; herbivore; [secondary] consumer; predator; prey; carnivore) enhances the response.

Score Level 4 Anchor Paper

This response shows a full and complete understanding of the question. The ecological role of every organism is integrated into the description of the effects of an urchin decline (an increase of the kelp population because it lost a predator; kelp crab would diminish because the sea otters would prey on them more often after losing a food source, and the sea otter population would also decrease in time). The supporting details are pertinent and complete, and the use of accurate scientific terminology ([first degree] consumer; herbivore; [second degree) consumer; carnivore; predator; prey) enhances the response.