Crayfish are invertebrates which means they don't have a backbone. They are also arthropods, which means that they have a protective exoskeleton on the outside of their body. Other arthropods include insects, spiders, and centipedes. Crayfish continually shed their exoskeleton and regrow a new one. During this transition is when they are most vulnerable to predators because they aren't protected by their outer shell.
Crayfish are found all over the world in many different freshwater environments, such as rivers, creeks, springs, and swamps. But this doesn't necessarily mean that you will be able to find them. They are somewhat cryptic because they dig out homes for themselves under rocks and blend in well with their environment. Crayfish will ardently defend this dwelling against intruders using their strong front claws
After passing through the cornea, light travels through the pupil (the black dot in the middle of the eye). The iris—the circular<span>, colored area of the eye that surrounds the pupil—controls the amount of light that enters the eye.</span>
Animal cells contain dna enclosed in the nucleus
Answer;
A. Movement in his lower extremities
Explanation;
-The 1st lumbar vertebra or the L1 vertebra is the smallest and most superior of the lumbar vertebrae. As the first vertebra in the lumbar region, the L1 vertebra bears the weight of the upper body and acts as a transition between the thoracic and lumbar vertebrae.
-The lumbar vertebrae contain spinal cord tissue and nerves which control communication between the brain and the legs.