Which layer of the alimentary canal is constructed from either stratified squamous or simple columnar epithelium?

Mucosa

Explanation:

The gastrointestinal tract or alimentary canal consists of four main layers:

•Mucosa- consists of the epithelium (it can be stratified squamous or simple columnar epithelium) together with glandular tissue and the lamina propria  (connective tissue)

•Submuscosa- consists of fibrous connective tissue with larger blood vessels, lymphatics, nerves..

•Muscularis externa-smooth muscle layer that consists of three layers, responsible for movement (propulsion) and physical break down of the food

•Serosa-consists of connective tissue continuous with the peritoneum.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.