Marine Annelid Worm Research Articles

Oxygen affinities of respiratory blood pigments in Serpula.

Serpula, a marine annelid worm, is the only animal known to possess two respiratory pigments in its blood, namely, chlorocruorin and haemoglobin1.

On chlorocruorin and haemoglobin

Chlorocruorin is a dichroic red-green respiratory protein. It is chemically similar to haemo­globin, and is only found dissolved in the blood of certain marine annelid worms. Chlorocruorin is the characteristic blood pigment of the Serpulimorpha (serpulids and sabellids), but in the genusSerpulaboth chlorocruorin and haemoglobin are present together in the blood. This is the first time that two respiratory pigments have been found in the blood of one animal. Young individuals have relatively more haemoglobin, older ones more chlorocruorin. Within the serpulid genusSpirorbis, one species has chlorocruorin in its blood, an other has haemoglobin, while a third has neither pigment. As their habitats are similar, no functional explanation for these differences suggests itself. The oxygen affinity of all chlorocruorins tested is considerably lower than that of most haemoglobins. But inSerpulathe oxygen affinities of the chlorocruorin and haemoglobin are the same as one an other. The carbon monoxide affinity of chlorocruorin (inBranchiomma) is higher than that of any haemoglobin. Although Serpulimorpha have chlorocruorin in their blood, the haem present in their tissues (muscles, eggs, sperm ) is protohaem, not chlorocruorohaem. One genus,Potamilla, with chlorocruorin in its blood, has haem oglobin in the muscles. Chlorocruorin is known only from blood, and from the mucous tube ofMyxicola; none has been found in cells. Coelomic fluid contains none. Protohaem is secreted in to the protective tubes of both serpulids and sabellids. A proto-haemochromogen is present in the gut fluid of serpulids, recalling that found in crustaceans and molluscs.

Carbon Monoxide Affinity of Chlorocruorin and Hæmoglobin

CHLOROCRUORIN, the green-red respiratory blood pigment of certain marine annelid worms, is the only known substance built on the same plan as haemoglobin. Like most kinds of haemoglobin, chlorocruorin has a higher affinity for carbon monoxide than for oxygen1. This property, valueless to animals, is utilized in experimental work to eliminate the possible respiratory activity of these pigments and so to test their functional significance2,3. The relative affinity of chlorocruorin (Ch), or of haemoglobin, for the two gases in the reversible reaction is given by the equilibrium constant K in the equation , from which it is seen that when the pigment is 50 per cent in the carboxy state and 50 per cent in the oxy state, K becomes the ratio of oxygen to carbon monoxide.

The identity of some marine annelid worms in the United States National Museum

The identity of some marine annelid worms in the United States National Museum