Question

1) Which of the worms (flatworms, roundworms, or earthworms) shows segmentation? What are the advantages of having a segmented body?

2) Describe the adaptations that have allowed squid to evolve a predatory, highly active lifestyle.

Answer 1

1. Annelida is a group, which include segmented worms. Earthworms show segmentation.

The advantages of segmented body:

Segmentation provides movement of an organism.

It protects its sensitive organs from damage.

The ability to divide functions into different portions of the body, which permits an organism to perform increasingly complex activities and use different segments to perform varying functions.

Segmentation helps with the hydrostatic skeleton and muscle contractions by permitting the animal to contract only a few segments at a time, therefore expend less energy.

2) Squids are the most abundant cephalopods on the planet. They found from the deepest oceans to the shallow seas. These adaptations are helpful in the wild to survive, from unique body shapes to specialized limbs.

Torpedo-Shaped Bodies - Squid have torpedo-shaped bodies, which make them extremely aerodynamic. They suck in water by the help of a tube and then expel it. It allows them to escape from dangerous predators like sharks, dolphins, sea turtles, seals and even humans, who hunt squid for their commercially sold meat.

Ink - They produce ink and keep it in an ink sac near their rectum. They can expel this ink in the face of a predator for creating confusion and permitting it to escape.

Big Eyes - Squids have among the largest eye size to body size ratio in the entire animal kingdom. They use these large eyes to bring in as much light as possible at night, when they hunt and to see in the depths of the deep seas where no sunlight reaches.

Tentacles - Squids have 10 tentacles protruding from the base of their elongated torpedo-bodies. Two of the squid's arms are over four times the length of the other arms. They used to catch fish and other prey.

Beaks - Squids have powerful beaks centered at the base of their heads in between their tentacles. These beaks are most powerful and are used not only to chew food but to crush crab and mollusk shells, making them easier to swallow.