When zebrafish eggs are laid, they are surrounded by a tough chorion. Sperm are unable to get through this chorion and must find the tiny tunnel called a micropyle that provides a channel to the egg cell membrane. This channel is so tiny that only one sperm is able to fit through at a time. The micropyle most likely.

Aids in preventing polyspermy.

Explanation:

Polyspermy is a process that involves multiple fertilization of an egg by multiple sperm, which leads to the embryo inheriting multiple centrioles from the parents. Polyspermy is often considered lethal, and there are several mechanisms in most animals that prevents multiple fertilization of eggs. One of such mechanisms is the possession of a micropyle by zebrafisg eggs which limits the chances of multiple fertilization, as only one sperm is able to pass through the micropyle at a time. This micropyle most likely aids in preventing polyspermy.

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.

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.