Study on the Development of Spiral babylonia snail Tiger Snail Juvenil Eggs (Babylonia spirata Linnaeus, 1758) in the Laboratory

Several marine gastropods are known to have high economic value, one of which is the Spiral babylonia snail. They commonly exploited for meat, shell, or operculum. Tiger snail meat is commonly exported and consumed by fishermen. Its shell is used as a material for industrial lime and for omamen. Operculum is commonly used as a medicinal and perfume ingredient). However, the recent production has decreased due to the limited information of seasonal catch. One way to overcome these obstacles is through culture activities. The provision of seeds is an important link in the culture system, therefore the study of the spawning process and larval development is an important requirement for the development of larval rearing techniques. This study aims to determine the development process of juvenil eggs and the survival rate of tiger snails reared in the laboratory.. The study was conducted at the Laboratory of Marine Farm Subdivision in Kudus, Pt Pura Bahari, Jepara Regency. This sudy used experimental method with descriptive data analysis. Adult tiger snails were caught from Bunga waters, Demak. The snails were reared in a rectangular tube filled with 15 cm filtered sea water and 5 cm of sand. Egg capsules were reared in a 4 liters circular tube with continuous aeration. The hatched larvae were reared in a 300 liters circular tube filled with filtered seawater, continuously aerated and fed with Chlorella plankton . Our result showed that tiger snails spawn naturally and produce egg capsules. The incubation period for the capsule is 6 days, then develop into veliger larva for 12 days. The veliger larvae metamorphosed,and become juvenil. The lowest survival rate observed in the veliger stage. The survival rate of the egg and the intracapsular trochopore stages were quite high (tube I = 98.413%; tube II = 98.238%; tube III = 90.476%), then the lowest was in the veliger stage (tube I = 3,468%; tube II = 2.603%; tube III = 2,598%) and the juvenil stage is quite high compared to the previous phase (tube I = 3,413%; tube II = 2,479%; tube III = 2,351%).

An unusual suctorial montacutid bivalve from the deep Atlantic

The shell and internal anatomy of the montacutid bivalve Mysella verrilli is described for the first time. The species is remarkable in that the oesophagus has developed into a suctorial proboscis. This has been accompanied by the loss of the palps. In addition the gonads have been extended from the dorsal part of the body to form two gill-like extensions to which the reduced inner demibranchs attach along the postero–ventral margin. Mysella verrilli broods its young in the mantle cavity to the late veliger stage before releasing them. It is believed that the species is probably a suctorial ectoparasite on a soft-bodied benthic invertebrate.

Eggs, larvae, and spawning in Melarapha cincta (Quoy & Gaimard) and M. oliveri Finlay (Littorinidae, Gastropoda)

Both the New Zealand species of Melarapha, M. cincta and M. oliveri, laid minute planktonic egg capsules, of the "Drum" type, in the laboratory. Capsules were similar in the two species, but could be distinguished in side view by shape. Eggs developed rapidly, hatching at an early veliger stage in 3-4 days at room temperature. Attempts to rear these very small larvae were not successful, but later veligers, taken from plankton hauls, were reared through metamorphosis and identified as Melarapha. Veliger stages are drawn and described and the length of planktonic life assessed as 1-2 months. The two species are indistinguishable after hatching until many months after metamorphosis when the adult coloration of the shell is developed. Spawning was studied at Portobello in a mixed population of M. cincta and M. Oliveri extending from high HWS to low HWS. The breeding season was from November to March. Spawning, in animals associated with rock pools, occurred intermittently and not particularly during spring tides. The presence of egg capsules of both species in rock pool samples was associated ( χ² tests) with a rock pool salinity of 33-36‰ and with the occurrence of rough weather.

CHLOROPLASTS AS FUNCTIONAL ORGANELLES IN ANIMAL TISSUES

The marine gastropod molluscs Tridachia crispata, Tridachiella diomedea, and Placobranchus ianthobapsus (Sacoglossa, Opisthobranchia) possess free functional chloroplasts within the cells of the digestive diverticula, as determined by observations on ultrastructure, pigment analyses, and experiments on photosynthetic capacity. In the light, the chloroplasts incorporate H14CO3- in situ. Reduced radiocarbon is translocated to various chloroplast-free tissues in the animals. The slugs feed on siphonaceous algae from which the chloroplasts are derived. Pigments from the slugs and from known siphonaceous algae, when separated chromatographically and compared, showed similar components. Absorption spectra of extracts of slugs and algae were very similar. The larvae of the slugs are pigment-free up to the post-veliger stage, suggesting that chloroplasts are acquired de novo. with each new generation.