Question

Haemocoel occurs in
(A) Coelenterata
(B) Porifera
(C) Annelids
(D) Arthropoda

Answer 1

Hint: Coel represents the cavity. Haem represents the haem part of haemoglobin present in the Red blood cell. Haemocoel is the blood containing body cavity. Other kinds of body cavities are: Pseudocoelomates and acoelomates.

Complete answer:
Coelom is the body cavity which is present between the body cavity and gut. There are found different terms on the basis of coelom:
Acoelomates: Animals lacking coelom are categorized under acoelomates. Example: Platyhelminthes, Coelenterata etc.
Coelomates: Animals bearing coelom are categorized under coelomate. Annelida to chordata.
Pseudocoelomates: Pseudocoelomates are those organisms which have mesoderm in the scattered pouch form. Example: Aschelminthes.
Haemocoel is made up of two words: “Haem + coel”. Coel is the body cavity and haem represents the haem part of haemoglobin. Hence haemocoel are those organisms which have circulatory fluid in the body cavity. Haemolymph is the circulatory fluid present in the hemolymph. It consists of nutrients, hormones and also contains excretory wastes. Haemocoel is found in the arthropoda and mollusca phylum.

That’s why the correct answer is “Arthropoda”.

Note:
Molluscs also contain haemocoel. Because they have haemocoel. Arthropods and molluscs have haemocoel. They have a blood-filled body cavity. From Aschelminthes to chordates, all organisms have acoelomate. Platyhelminthes have pseudocoelomates. Poriferans, coelenterata and ctenophora have acoelomate condition.