TASK DEFINITION: Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
PROBLEM: Fact 1: Echinoderms use pheromones to communicate with each other. 
Fact 2: Echinoderms are represented by the starfish.

SOLUTION: Starfish use pheromones to communicate with each other.

PROBLEM: Fact 1: a beak is used for catching prey by some birds. 
Fact 2: Pelicans are migratory birds.

SOLUTION: Pelicans use beaks for catching prey.

PROBLEM: Fact 1: Male dogs use pheromones in urine to mark their territory. 
Fact 2: For a male, urine markings are used to define the boundaries of their territory.

SOLUTION:
male dogs use pheromones in urine markings to define boundaries.