(a) Open Circulatory System

Closed Circulatory System

In this type of circulation, blood flows in spaces called sinuses and the cells and tissues are directly bathed in it.

e.g., arthropods (grasshopper, cockroach), gastropods (snail).

In this type of circulation, blood is circulated via a series of vessels (arteries, veins and capillaries).

e.g., annelids (earthworm) and  vertebrates (birds, primates etc)

(b) Oviparous characteristics Animals

Viviparous Characteristic Animals

Oviparity is expulsion of undeveloped eggs rather than live young ones

Animals that lay eggs are called Oviparous.

e.g, fishes, reptiles, amphibians, birds, insects and monotremes (mammals that lay eggs).

Viviparity is retention and growth of fertilised egg within the material body until the young one is capable of independent existence,

Animals which give birth to their young ones and are called viviparous animals, e.g., Mammals.

(c) Direct Development

Indirect Development

Direct development is the type of development in which there is no larval/nymphal or other intermediate stages in life, cycle between the egg (or birth) and the adult (e.g., mammals)

Indirect development is mostly observed in lower animals. The adult individuals lay eggs, which develop Passing into the adult after Passing through few to several larval nymphal stages. (e.g,, echinoderms, arthropods)

(d) Acoelomate 

Pseudocoelomate

The animals without coelom are called as acoelomates.

e.g., sponges,  cnidarians, ctenophores and , flatworms.

The animals in which body cavity is derived from the blastocoel of the embryo are called pseudocoelomates.

e.g., roundworms.

(e) Notochord

Nerve Cord

Notochord is the skeletal rod which lies length wise between the central nervous system and the alimentary canal or the gut.

Vertebrates possess it at the young stage of development.

It is a part of skeleton system

In adults vertebrates, notocord is replaced by vertebral column.

Nerve cord is the solid strand of nervous tissue forming a part of central nervous system, especially in invertebrates.

(f) Polyp

Medusa

Polypis sessile and cylindrical form in Aurelia.

Polyp produces medusa asexually.

Medusa is umbrella shaped and free swimming form in Aurelia.

Medusa forms polyp sexually.