Evolution of Circulatory System

  

Sponges: Transport of nutrients by amoeboid movement.	The amoeboid cells within the wll act as a circulatory device to transport nutrients from cell to cell. (transport of nutrients by amoeboid movement) Eg: would pick up some food, move out to the sheets of cells that cover the surface and feed them.
Hydra/Polyp (Cnidarians): Diffusion	Nutrient molecules are passed by diffusion to rest of the body from cells of gastrodermis.
Flatworm/Tapeworm (Planarians): Diffusion	Since the body is flattened, nutrient molecules are easily passed by diffusion from cell to cell.
Roundworm: Nutrients and wastes in body cavity – no circulatory system.	(Circulatory and excretory) Food digested in gut is not distributed by any specialized vascular system. Nutrients and waste are distributed in body cavity, whole contents are regulated by one celled glands (in simples species) or excretory canal along each side of body.
Molluscs
Clam (Bivalve): Heart present in pericardial cavity, pumps blue blood which contain pigment hemocyanin (instead of red Hb), heart pumps blood to various organs in which blood is within vessels, open circulation.	Clam (bivalve) – The heart of a clam lies just below the hump of the shell within the pericardial cavity. The heart pumps blue blood, containing the pigment hemocyanin instead of red haemoglobin, into vessels that lead to various organs of body. Within organs, however, blood flows through spaces, or sinuses, rather than through vessels. Such a circulatory system is called an open circulatory system because the blood is not contained within blood vessels all the time This type of circulatory system can be associated only with an inactive animal because it is an inefficient means only with an inactive animal because it is an inefficient means of transporting oxygen and nutrients throughout the body.
Snail (Gastropod): Heart – 1 auricle and 1 ventricle Aortic trunk to tissues of the body through arteries and capillaries Hemocoel in tissues, open circulation	The heart of the snail is found on the left side and consists of one auricle and one ventricle. The ventricle pumps blue blood through an aortic trunk to all parts of the body through a series of arteries and capillaries. From capillaries, the blood passes into sinuses or spaces in the tissues called hemocoel. From hemocoel blood passes into veins and back to the auricle.
Octopus (Cephalopod): 3 hearts is present at end of each gills. Heart pumps blood throughgills and rest of body by 3rd heart.	They have blue blood and 3 hearts. There is a heart at end of each of their gills; these hearts pump blood through gills. The 3rd heart pumps blood through rest of body.
Annelids (Earthworm): Closed circulation, Dorsal blood vessel anteriorly, 5 pair of heart, pump into ventral blood vessels, pulsating vessels.	Earthworm has an extensive closed circulatory system. Haemoglobin containing blood moves anteriorly in a dorsal blood vessel and then is pumped by 5 pairs of hearts into a ventral blood vessel. As ventral blood vessel takes blood toward the posterior regions of the worm’s body, it gives off branches in every segment.
Arthropods (Insect): Open circulation, blood colourless, tubular circulation.	They have an open circulatory system. Colourless blood is pumped dorsally from heart and then enters sinuses where it comes in direct contact with the tissues. These sinuses are referred to as hemocoel.
Echinoderms (Starfish):	Coelomic fluid, circulated by ciliary action, performs many of the normal functions of a circulatory system.
Chordates: Closed circulatory system, red blood.	All vertebrates have a closed circulatory system in which red blood is contained entirely within blood vessels. They have ventral heart within 2-4 chambers.
Fishes: Atrium and ventricle (no division of Rt and Lt)	The heart of a fish is a simple pump and the blood flows through chambers, including a non divided atrium and ventricles, to the gills only. Oxygenated blood leaves the gills and goes to the body proper.
Amphibians: Heart - 2 auricle and 1 ventricle, heart has pericardium, blood is pumped both to lungs and skin.	With the development of lungs, there is a change is circulatory system. The amphibian heart has a divided atrium but a single ventricle. The right atrium receives impure blood from the lungs that has just been oxygenated but these 2 types of blood are mixed partially in the single ventricle. Mixed blood is then sent, in parts, to the skin, where further oxygenation can occur. The frog heart is the only organ contained within coelom, which has its own protective covering. This is pericardium.
Reptiles: Heart separated Rt and Lt but division of ventricles none.	The atrium of the heart is always separated into right and left chambers but division of ventricles varies. There is always at least one inter ventricular septum, but it is incomplete in all but the crocodiles, therefore exchange of oxygen and deoxygenated blood between ventricles occur in all except the crocodile. Reptiles do not regulate their body temperature. Animals that cannot maintain a constant temperature Eg: Fishes, amphibians and reptiles are cold blooded. They take on the temperature of external environment. Most reptiles try to regulate body temperatures by exposing them to the sun if they need warmth or by hiding in the shadows if they want to cool off.
Birds: 4 chambers – complete separation of oxygenated blood from deoxygenated.	They have a four chambered heart that completely separates oxygenated blood from deoxygenated blood. Birds are warm blooded; like mammals, they are able to maintain a constant internal temperature. They may be associated with their efficient nervous, respiratory and circulatory system
Mammals: Pulmonary and systemic circulation, double circulation.	Mammal circulatory systems are divided into 2 circuits: pulmonary and systemic. The pulmonary circuit carries deoxygenated blood from heart to respiratory surface in the lungs where it is reoxygenated and then back to heart. The systemic circuit carries oxygenated blood to all the body’s cells via arteries and deoxygenated blood back to heart via veins. The mammalian double circulatory system is efficient because it uses a separate pump (2 ventricles) to power each circuit.
Primates: 4 chambers, double circulation, maintain constant body temperature.	Like other mammals, primates have 4 chambered heart and a double circuit circulatory system and are able to maintain a constant body temperature. The insulating covering is provided by hair, although in humans nearly all hair is lost and the insulation is now provided by clothing.