440 



FURTHER EVOLUTION 



Table 4. Biological Distribution of Haemoglobins 



Phylum 



Pigment 



Examples 



Protozoans 



Haemoglobin in 

 cytoplasm 



Ciliate paramecia 



Nematodes 



Erythrocruorin 

 in body cavity 



Myohaemoglobin 

 in body wall 



Several species of Ascaris, intestinal 

 parasitic worm in mammals. Two 

 pigments different in character 



Annelids 



Erythrocruorin 

 in plasma 



Erythrocruorin 



Chlorocruorin 

 in plasma 



Scattered throughout phylum, e.g. 

 Arenicola, the lug worm, or Lum- 

 bricus, the earth worm 



Several species of order Polychaeta, 

 e.g. Glycera, the blood worm 



Several species of order Polychaeta, 

 e.g. Spirographis, a marine worm 



Arthropods 

 Crustaceans 



Insects 



Erythrocruorin 

 in plasma 



Found in several species, e.g. Daphnia, 

 water flea, class Branchiopoda and, 

 e.g., Ernoecera, parasite in fish, class 

 Copepoda 



Erythrocruorin 

 in plasma 



Chironomus, midges (order Diptera) 



Molluscs 



Erythrocruorin 

 in plasma 



Erythrocruorin 

 in corpuscles 



Myohaemoglobin 



Planorbis, fresh water snail (order 

 Gastropoda) 



Area, a mussel (order Lamellibranchi- 

 ata) 



Busycon, a whelk (order Gastropoda). 

 Pigment in heart and radula muscles 

 (haemocyanin in circulation) 



Echinoderms 



Erythrocruorin Thyone, sea slug (class Holothiiroidea) 



Chordates 



Protochordates 



Vertebrates 



So far, neither haemoglobin nor myo- 

 haemoglobin reported present in 

 members of this subphylum. Red- 

 field reports absence of haemoglobin 

 in Amphioxus 



Haemoglobin 

 in corpuscles 



Myohaemoglobin 



Present throughout, including Lam- 

 petra (suborder Cyclostomata) 



Probably present throughout, in lower 

 orders, e.g. Pisces, Amphibia, and 

 Reptilia, mostly in heart muscle 



