Secretion of a Highly Sulphated Acid Mucopolysaccharide by the Brittle-star, Ophiocomina nigra
THE secretion of a mucus from the tube-feet of ophiuroids is well known1, although the chemical nature of this substance has not been investigated. In a study of the feeding mechanisms of ophiuroids, I find that Ophiocomina nigra (Abildgaard), a common littoral species widespread in the north-east Atlantic and Mediterranean, in addition to the mucin of the tube-feet, secretes all over the body surface an abundant mucus used in conjunction with a detritus-feeding mechanism. Attempts to find the source of this secretion have revealed two types of mucus glands previously undescribed for the species.
Secretory cells in the foregut of the echinopluteus
SummaryMetachromatically-staining substances have been found in the secretion of the stomodeum and esophagus of the echinopluteus (Psammechanus miliaris). This secretion seemed to derive from specialized cells in the wall of the foregut. Ultrastructural examination revealed that these cells are rich in large cisternae containing an electron-translucent material. They are also rich in ribosomes and possess large Golgi complexes. The number of secretory cells increases with age. It is tempting to speculate that the function of these cells is analogous to that of the glandular cells of the endostyle in some chordate phyla.
The incidence of dead and dying fish in the Moray Firth, September 1963
Dead and dying fish were reported from the Moray Firth during a period of 15 days in September 1963. The initial mortalities were in the inner Firth, but they later spread outwards, especially eastwards along the southern shores of the Firth. Mass mortalities of the lugworm (Arenicola marina) also occurred in Scottish waters in 1962 and 1963, and at Balintorein Easter Ross fish and lugworm mortalities were contemporary.