Will all the organism have blood in animalia ? If not why?
“Do all animals have blood?”. The answer is No.
Marine sponges are still considered animals and yet they have no circulatory system and thus no blood. However most “advanced” (eg further along the evolutionary tree) have blood. Animals of phyla up to and including Nematoda do not have a circulatory system and thus cannot have blood. However,by the time of the the next phylum and up up, the segmented worms(Annelida) animals start having a circulatory system and thus can have “blood”. Mollusk and crustaceans have blood, however it is not red. It is blue because the oxygen pigment is hemocyanin a copper based compound. Insects also have something akin to blood, it is called hemolymph because an insect circulation system is “open” (the piping doesn't run all the way back, instead the blood accumulates and diffuses back). Also, hemolymph usually doesn't contain a oxygen carrying pigment because most insects are small enough that they get enough oxygen through diffusion from the air system. Thus insect blood is mostly clearish yellowish. Only vertebrate blood is red.
“Do all animals have blood?”. The answer is No.
Marine sponges are still considered animals and yet they have no circulatory system and thus no blood. However most “advanced” (eg further along the evolutionary tree) have blood. Animals of phyla up to and including Nematoda do not have a circulatory system and thus cannot have blood. However,by the time of the the next phylum and up up, the segmented worms(Annelida) animals start having a circulatory system and thus can have “blood”. Mollusk and crustaceans have blood, however it is not red. It is blue because the oxygen pigment is hemocyanin a copper based compound. Insects also have something akin to blood, it is called hemolymph because an insect circulation system is “open” (the piping doesn't run all the way back, instead the blood accumulates and diffuses back). Also, hemolymph usually doesn't contain a oxygen carrying pigment because most insects are small enough that they get enough oxygen through diffusion from the air system. Thus insect blood is mostly clearish yellowish. Only vertebrate blood is red.
