Melbourne R. Carriker

Predatory Behavior of a Shell-Boring Muricid Gastropod

Invertebrate animals in a wide range of taxa have evolved complex mechanisms for excavating boreholes through the mineralized exoskeletons of live prey to obtain food. Although the mechanism of penetration has been the subject of increasing research in recent years (Carriker et al., 1969), predatory behavior has received less attention (Carriker and Smith, 1969).

Gastropod Urosalpinx: pH of Accessory Boring Organ while Boring.

Recent development of a microelectrode has enabled the first continuous recording of the pH of the secretion of the normally functioning accessory boring organ of the shell-boring predatory snail Urosalpinx. The recording was made in an incomplete borehole in a glass-shell model. The minimum pH recorded was 3.8; hitherto the secretion had been considered neutral.

REGENERATION OF THE PROBOSCIS OF MURICID GASTROPODS AFTER AMPUTATION, WITH EMPHASIS ON THE RADULA AND CARTILAGES

Boring of prey shells by muricid gastropods involves the close interaction of the proboscis, propodium, and the accessory boring organ (ABO) in a predictable cycle which repeats itself continuously throughout the process of boring of each borehole. Although the radula serves only a minor part in shaping the borehole, it appears that both the radula and the ABO are necessary to effect normal penetration ( Carriker and Van Zandt, 1972) . Whether this is so could be tested by inactivation of one and then the other organ in different individuals and noting the effect on penetration. The first objective of the present study was to examine the effect of removal of the proboscis on boring. In 1957 an adult Urosalpinx cinerea in our laboratory caught its proboscis be tween the glass and shell of an oyster model (Carriker and Van Zandt, 1972) , and after tugging for some time to free itself, tore away the proboscis leaving the distal third wedged in the model. The snail recovered and resumed boring of prey in 20 days. The previous year Demoran and Gunter ( 1956) experimentally ampu tated the distal portion of the proboscis of several thaisid boring snails, Thais haemastoma, and reported that these gastropods regenerated the proboscis within three weeks provided the organ had been cut off cleanly. From time to time the senior author has dissected large adult Urosal/inx cinerea collected in the field in which the anterior portion of the proboscis, though abnormally small, externally appeared morphologically normal. The small size of the proboscis tip indicated that these snails had accidently lost and regenerated the proboscis. These several ob servations suggest that regeneration of the complex buccal mass in Urosalpinx cinerea (Carriker, 1943) and other predatory marine gastropods may occur nor mally in nature. The second objective of this investigation was thus to determine how commonly and at what rate regeneration occurs in the laboratory after experi mental proboscisectomy. A preliminary summary of the results of these studies was published by Carriker (1959, 1961). The radula, being a relatively hard struc ture (Carriker and Van Zandt, 1972) provides a readily measurable parameter for quantitative determination of regeneration. During the past several decades regeneration of cartilages has been investigated almost exclusively in vertebrate animals. Recently, however, following a long period of neglect, invertebrate cartilages again came under serious study (Person and Philpott, 1969; Mathews, 1968). As part of a survey of the nature and prop 317

PENETRATION OF MOLLUSCAN AND NON-MOLLUSCAN MINERALS BY THE BORING GASTROPOD UROSALPINX CINEREA

1. Results of an experimental study of the capacity of Urosalpinx cinerea follyensis Baker to penetrate 15 kinds of molluscan and abiogenic minerals are reported. Minerals, cut into small wafers, and radular teeth were exposed to penetration by normally boring snails in valve models. Depth of incomplete boreholes was measured with a compound microscope. Extent of dissolution was examined with a scanning electron microscope. All biogenically formed calcareous minerals, except radulae of U. cinerea, and some abiogenic minerals, were penetrated. Rate of penetration of wafers decreased in the following order: calcite and aragonite (shell of Crassostrea virginica, Spisula solidissima, Anomia simplex), strontianite, bone and tooth hydroxyapatite, anhydrite, witherite, and magnesite. Abiogenic minerals siderite, smithsonite, alunite, fluorite, and quartz were not penetrated. Of the 15 tests performed on biogenically formed calcareous minerals, only two snails (or 13%) left the sample on the model before the expe...

ULTRASTRUCTURAL EVIDENCE THAT GASTROPODS SWALLOW SHELL RASPED DURING HOLE BORING

1. Observations are reported on the ultrastructure of shell material rasped by Urosalpinx cinerea follyensis Baker from boreholes in the valves of Mytilus edulis Linne and transported normally to the stomach through the buccal cavity and esophagus. Duration of the period of chemical activity by the accessory boring organ and rasping by the radula were determined with a valve model. Pellets of shell raspings were removed from the stomach and, after fracturing to reveal the interior, and coating with metal, were studied with the scanning electron microscope. Shell raspings were compared with prisms and lamellae in fracture surfaces of normal shell of M. edulis and shell etched with ethylenediamine and sodium hypochlorite to reveal the form of shell units clearly.2. The study provided ultrastructural evidence for the first time that Urosalpinx cinerea swallows shell rasped from the borehole during penetration of prey. Both prisms and lamellae were identified in the pellets removed from the stomach. Noticeabl...

Activity of the marine gastropod Urosalpinx cinerea in the absence of hibernation

Activities of two populations of the oyster borer,Urosalpinx cinerea follyensis Baker, deprived of hibernation in warmed running seawater are described. Seawater was warmed in a nontoxic system lacking moving mechanical parts. Survival, addition of shell, crawling, turning over; identification, mounting, boring, and consumption ofCrassostrea virginica andMytilus edulis; pH of secretion of the accessory boring organ; size and shape of boreholes; deposition and form of egg capsules and development of young, appeared normal. Relatively constant environmental conditions for prolonged periods made the snails sluggish. While maximum deposition of egg capsules occurred in July, small clusters were oviposited sporadically during the remainder of the year. Successful growth and reproduction in the absence of hibernation demonstrated that this snail, unless carefully controlled, could become a serious predator in ponds warmed by coolant seawater from power stations for shellfish culture.

ENZYMES OF THE ACCESSORY BORING ORGAN OF THE MURICID GASTROPOD UROSALPINX CINEREA FOLLYENSIS. I. AEROBIC AND RELATED OXIDATIVE SYSTEMS

1. Histochemical observations of the aerobic metabolism of the accessory boring organ (ABO) of Urosalpinx showed that cytochrome oxidase, succinate dehydrogenase and lactate dehydrogenase activities are localized in the secretory cells of the distal secretory disk.2. Correlated biochemical assays of cytochrome oxidase activity of whole homogenates of the ABO prepared from active snails gave specific activities which ranged between 0.190 to 2.10.3. There were no differences in cytochrome oxidase specific activities using ABO whole homogenates from resting or drilling snails. However, the specific activities of mitochondrial-rich particulate fractions isolated from whole homogenates by high speed centrifugation showed that oxidase activities of drilling specimens were 1.040 as opposed to 0.639 for samples from resting specimens.4. Snails did not bore shells of the oyster Crassostrea virginica when maintained in a N2 atmosphere, and ceased boring begun prior to transfer to anaerobic conditions.5. These data ...