Novel activities of saliva from the octopus Eledone cirrhosa (Mollusca; Cephalopoda).

Haemolytic activity against mammalian erythrocytes was detected in very low concentrations of saliva from the octopus Eledone cirrhosa. It was not caused by any previously identified component of this saliva. The activity was slightly inhibited by trypsin and more drastically by chymotrypsin. Locust bioassay was used to test HPLC fractions isolated from E. cirrhosa saliva. An LD(50) of 378.4 microg/g locust weight was calculated for whole saliva injected into the desert locust Schistocerca gregaria. This study was the first record of haemolytic activity and toxicity to insects in cephalopod saliva. Both haemolytic and insecticidal fractions could be separated using reversed phase HPLC.

Methods for the aquarium maintenance of the common octopus of British waters, Eledone cirrhosa.

Healthy, undamaged specimens survive well in recirculating aquarium seawater of about 36 parts per thousand salinity and PH 7.4, having 50 mg.1(-1) nitrogen as nitrate, less than 0.1 mg.1(-1) nitrogen as nitrite, nitrogen as nitrate, and less than 0.1 mg.1(-1) nitrogen as ammonia, and a m ean annual temperature of 14-15 degree C, about 5 degree C above ambient. For maximal growth rates, the gross wet weight of liver crabs required as food ranges up to 10% of the weight of the octopus. Weight-specific growth rates fall from 3.4% day-1 at 100-200 g bodyweight, to 1-1.5% day-1 at greater than 500 g bodyweight. Survival of healthy, wild-caught animals, commonly 4.6 months and up to 8 months, is apparently limited more by endogenous factors concerned with sexual maturation and lifespan than by aquarium conditions. Eggs have been laid but it has not yet been possible to hatch and rear them.

Fine structure of the subradular organ of Lepidochitona cinereus (L), (Mollusca, Polyplacophora).

Electron microscopy of the subradular organ of the chiton Lepidochitona cinereus (L) reveals at least three cell types, microvillous, ciliated and mucus-secreting, situated in a single epithelium. The base of the epithelium is abundantly innervated and supplied with muscle cells. The fine structure is consistent with a chemosensory function for the subradular organ.

Receptor units responding to movement in the octopus mantle.

1. A preparation of the mantle of Octopus which is inverted over a solid support and which exposes the stellate ganglion and associated nerves is described. 2. Afferent activity can be recorded from stellar nerves following electrical stimulation of the pallial nerve. The latency and frequency of the phasic sensory response is correlated with the contraction of the mantle musculature. 3. It is proposed that receptors cells located in the muscle, and their activity following mantle contraction, form part of a sensory feedback system in the mantle. Large, multipolar nerve cells that were found between the two main layers of circular muscle in the mantle could be such receptors.

The aesthetes of chitons. III. Shell surface observations.

The shells of the chitons Lepidochitona cinereus, Sypharochiton pelliserpentis, Amaurochiton glaucus and Onithochiton neglectus were examined by scanning electron microscopy. In all species the surface terminations of the megalaesthete and micraesthete organs could be identified lying flush with the shell surface, as well as, lenses of the shell eyes in O. neglectus. Periostracal debris and encrusting diatoms were a usual feature of the shell surfaces. The micraesthete subsidiary caps normally appear featureless, but the megalaesthete apical caps sometimes appear to be perforated. The reasons for this perforate appearance are discussed and it is concluded that it provides no evidence for the normal passage of substances out of or into the megalaesthete.

The cardiac innervation of Eledone cirrhosa (Lamarck) (Mollusca: Cephalopoda).

The innervation to the cardiac organs and vessels of the octopods Eledone cirrhosa, E. moschata and Octopus vulgaris is described from vitally stained fresh material and wax-embedded sections. This innervation arises from the paired visceral nerves and includes two main peripheral ganglia (fusiform and cardiac) on each side. Several new details of the innervation are reported. Nerves supplying the lateral venae cavae arise from the ventricular nerves at the level of the ventricle. Nerve fibres run to the efferent branchial vessels from the cardiac ganglia. A small ganglion, lying on the auriculo-ventricular nerve, is described for some specimens of both species of Eledone, and is named the auricular ganglion. Commissural strands linking the right and left ventricular nerves of either side are found in Eledone, comparable to those previously described from Octopus. The detailed branching pattern of the innervation shows considerable individual variation and consistent interspecific differences. In E. cirrhosa the fine fibres innervating the inner and outer muscle layers of the auricle show distinct differences in their configuration. Innervation at the surface of the ventricular lumen and around the coronary arterial vessels shows evidence of specialization. The muscle of the branchial heart, particularly the valve leaflets at the junction of the heart and the lateral vena cava, is abundantly innervated. The observations are discussed in relation to other cephalopods and to their probable physiological significance. It is suggested that they provide evidence for a greater degree of neural influence in the control of the cardiac organs than is usually supposed and that they support the idea that the lateral venae cavae have a significant role in the generation of circulatory pressures.

Assignment of paternity groups without access to parental genotypes: multiple mating and developmental plasticity in squid.

We present a novel approach to investigating sibling relationships and reconstructing parental genotypes from a progeny array. The Bayesian method we have employed is flexible and may be applicable to a variety of situations in addition to the one presented here. While mutation rates and breeding population allele frequencies can be taken into account, the model requires relatively few loci and makes few assumptions. Paternity of 270 veined squid (Loligo forbesi) hatchlings from three egg strings collected from one location was assigned using five microsatellite loci. Paternal and maternal genotypes reconstructed for each of the three strings were identical, strongly indicating that a single female produced the strings that were fertilized by the same four males. The proportion of eggs fertilized was not equal between males in all three strings, with male 1 siring most offspring (up to 68% in string 1), through to male 4 siring the least (as low as 2.4% in string 1). Although temperature had a profound effect on incubation time, paternity did not affect this trait at 12 degrees C or 8 degrees C.