Which group of organisms is mostly characterized by having gill slits that extract oxygen from the water in which they live.

The kind of fertilization found in the majority of aquatic animals is (internal or external) fertilization.

Environmental impacts on evolution : mastery test

Some tools have graduations to show multiple measurements. for example, a ruler may have graduations for both millimeters and centimeters. when measuring the length of an earthworm, which graduations would allow for the most accurate measurement? millimeters centimeters decimeters meters