The peculiar and exacting environment of Tigriopus fulvus is discussed and a census of Tigriopus from a series of pools in the Isle of Man is given.Experiments have been made determining the resistance of Tigriopus to desiccation and its revival in favourable circumstances.The life history has been worked out, times taken in development noted, and the various stages compared and contrasted with those described by Guiglia.Sex can be determined at the fourth copepodid stage. Females are normally fertilised as fifth copepodids, but the males are not functional until the adult stage. A single female may produce several egg sacs giving rise to living nauplii from a single fertilisation.There is no evidence for parthenogenesis.
The feeding behaviour of eight species of medusae was studied; total food consumed, rates of digestion, and growth rate were noted, especially in Cyanea and Aurelia.Aurelia up to 5 cm diam can accept a wide range of size of food organisms obtained by filtering sea water through the curtain of tentacles during pulsation, whereas most other species find their food by random contact with the tentacles. In Bougainvillia it is the dichotomously branched oral tentacles that capture the food. The apparent selectivity of Sarsia in feeding on copepods is shown to be a physical effect produced by its method of swimming. Leuckartiara can catch and eat active organisms larger than itself. None of the medusae examined showed any reaction to artificial stimulation by a vibrating probe.The method of transfer of food from the tentacles to the mouth is closely associated with the structure of the medusa. Long trailing tentacles contract and lift food towards the mouth and if the manubrium is long it can be manipulated to pick off the food from the tentacles. If the tentacles are short the umbrella edge folds inwards towards the mouth. If there is no manubrium, as in Staurophora, the cruciform stomach can accept food at any point.Larval fish are important in the diet of most medusae and rough estimates are given of a probable consumption of 50–250 larval fish per hydromedusa, about 450–500 by each Aurelia, and in the order of 15,000 by Cyanea. A conversion factor is given for food eaten by medusae of 37%, though this is based on only few data.Following the work of Horridge and Boulton (Proc. Roy. Soc. (Ser. B) 168: 413–419, 1967), who found that Spadella could be artificially stimulated to bite vibrating probes, similar experiments were made with Sagitta elegans. Although the chaetognaths were successfully kept alive the probes produced no feeding reaction. The methods are outlined for the benefit of others wishing to continue such investigations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.