Tegula Funebralis Research Articles

Predator influence on shore-level size gradients in Tegula funebralis (A. Adams)

Reproductive portions of Tegula funebralis (A. Adams) populations are shown to be immune to seastar predation through a combination of predator preference for larger snails and a withdrawal behavior that favors the escape of smaller snails after capture by a seastar. Experimental addition of Pisaster ochraceus (Brandt) in winter causes changes in the intertidal distribution of Tegula funebralis similar to those observed during the summer increase in seastar numbers. It is suggested that these results supplant the hypothesis that lowered prereproductive mortality influences formation and maintenance of vertical size gradients in the lower intertidal zone.

Chemical mediation of invertebrate defensive behaviors and the ability to distinguish between foraging and inactive predators

When the predatory sea star Pycnopodia helianthoides was placed upstream, the sea urchin Strongylocentrotus purpuratus responded defensively by extending and opening its globiferous pedicellariae. No pedicellaria response was given in control seawater or when the sea star was downstream. The snail Tegula funebralis responded by moving up vertical surfaces when Pycnopodia helianthoides or when Pisaster ochraceus were placed upstream. When these sea stars were introduced downstream, the snail's response was not significantly different from that in control seawater. Water collected from an aquarium containing a single sea star was sufficient to trigger the response of S. purpuratus and T. funebralis; the physical presence of the sea star was not essential. This indicated that a chemical stimulus was involved, and the lack of responses when sea stars were downstream argued strongly against the possible additional involvement of visual or vibrational stimuli. S. purpuratus gave stronger pedicellaria responses to water flowing over an active Pycnopodia helianthoides than to water flowing over the same sea star when it was inactive. The significance of the ability to distinguish between actively foraging and inactive predators is discussed, and a mechanism is proposed to explain differences in the amount of stimulatory chemicals released by active and inactive sea stars.

Latitudinal variation in the life history features of the black turban snail Tegula funebralis (Prosobranchia: Trochidae)

At higher latitudes along the west coast of the USA the herbivorous intertidal snail Tegula funebralis (Adams, 1854) lives longer, grows more slowly, but attains a larger size than further south. To the north, age distributions are less predictable and often far from stationary. The differences, which have some generality, can be explained either by a primary temperature effect joined with increased hazards to planktonic larvae in the north, or else may result from a combination of interactions between intensity of predation, population density and food supply. Growth rates of transplanted individuals suggest a genetic basis for the latitudinal differences.

Trophic complexity in a littoral boulderfield

A food web constructed for the major invertebrate carnivores in a littoral boulderfield suggests that trophic complexity was very low. Each of the predators consumed several prey species but monopolized one or two species, producing a sharp partitioning of food resources. Spatial heterogeneity and differences in feeding behavior reinforced this pattern. The distributions of bored shells of Protothaca staminea and Tegula funebralis among the size classes of empty shells available in the boulderfield suggested that their primary predator, Octopus, had no size preferences.

"New" sense organ of primitive gastropods.

AN array of distance chemoreceptor organs sensitive to the scent of predatory starfish has been found on the ctenidial leaflets of the marine snail Tegula funebralis Adams. Each leaflet has one such organ; a slight swelling of the efferent border of the leaflet near the base marks its position. The swelling is cut across by a notch whose dorsal wall is infolded to form a pocket lying within the swelling. The swelling with its notch and pocket is termed a bursicle (small pouch) (Figs. 1 and 2).

ENERGY FLOW IN A NATURAL POPULATION OF THE HERBIVOROUS GASTROPOD TEGULA FUNERRALIS1

The gastropod Tegula funebralis (A. Adams, 1855) is confined to the intertidal. At Mukkaw Bay, Washington, it typically occurs in patches of characteristic individual size structure. Various energy flow parameters have been determined for a high intertidal (+ 1.8 to +0.9 m) and a low intertidal (+0.6 to −0.15 m) subpopulation; these values were then combined in a 3:1 ratio to generate a composite population.Direct and indirect calorimetry and direct observation on the natural population suggest the following: Tegula spawns once per year; the dry weight‐shell diameter relationships for males and females can be expressed by a single regression; different caloric values characterize immature (5.2 kcal/ash‐free g), mature males (5.4), intermediately mature females (5.8), and fully mature females (6.1); rates of aquatic and aerial respiration are different (at 13.5C an average low intertidal individual, 211 mg dry wt, respires at a rate of 75 µl O2/hr in water and 43 µl/hr in air).The energy budget, in which ingestion was obtained by summation, suggests an assimilation efficiency of about 70%, a gross efficiency of growth of 16.7%, and an ecological efficiency of predators of 4.9%. Other efficiencies are discussed. In Tegula, 60% of energy transferred to other levels is to decomposers. Comparison of the rate of annual consumption by Tegula, 1,071 kcal m− 2 yr−1, and net primary production estimated by cropping, 1,167 kcal m−2 yr−1, indicate a near balance. Importation of primary production may be necessary to the maintenance of the rocky intertidal community at Mukkaw Bay.

The radular muscle myoglobins of the gastropod molluscs, Acmaea testudinaus scutum eschscholtz, Hauotis kamtschatkana jones, Tegula funebralis adams, Fusitriton oregonexsis redfield, and Thais lamellosa gmelin

1. 1. The radular muscle myoglobin of the gastropod mollusc Fusitriton oregonensis has been purified. 2. 2. Fusitriton carbonmonoxymyoglobin has a molecular weight of about 35,400 and is cleaved by p-hydroxymercuribenzoate into subunits of apparent molecular weight approximately 17,000. 3. 3. The amino-acid composition of the half molecule of Fusitriton radular muscle myoglobin is: Lys 16.5, His 83 Arg 3, 1 2 Cys 2 , Asp 1τ, Thr 8, Ser 8 Glu 9, Pro 4, Gly 14.5, Ala 24, Val 9.5, Ileu 5, Met 9.5, Leu 14.5, Tyr 2.4, Phe 12.5, Trp present. 4. 4. The radular muscle myoglobins of Aanata testudinalis scutum, Haliotis kamtschat-kaaa, Thais lamellosa, and Tegula funebralis all have apparent molecular weights of about 34,000. 5. 5. The radular muscle myoglobins of the gastropod molluscs are compared.

The Pisaster‐Tegula Interaction: Prey Patches, Predator Food Preference, and Intertidal Community Structure

The herbivorous gastropod Tegula funebralis is not highly ranked in a food preference hierarchy of its major predator, the starfish Pisaster ochraceus, and exhibits a persistent broad overlap with it in the rocky intertidal zone at Mukkaw Bay, Washington. Observations on Tegula over a 5—yr period indicate that it settles high intertidally, lives there for 5—6 yr, and then tends to migrate lower into contact with Pisaster. Tegula lays down an annual growth line permitting it to be aged and a growth curve constructed. Analysis of relative growth and reproduction indicates that beyond a certain size (16 mm) large individuals perform less well in the upper than those in the lower intertidal zone. Pisaster consumes 25—28% of the adult Tegula per year in the area of spatial overlap, based on analysis of the age structure of 6—17 yr old Tegula, and by direct estimates of the percentage of the standing crop consumed annually. The relationship between Pisaster and sex ratio, relative energy limitation and reproductive output (fitness) of Tegula is discussed for three subpopulations. It is suggested that the implied results of the interaction is typical of that between a major predator and one of its less preferred prey. The prominent zonation exhibited by preferred prey, the observed intimacy of association of predator and less preferred prey, and the zoogeographic homogeneity of the Pacific rocky coastline community are discussed in relation to three intermeshing ecological processes.

Studies on osmotic adjustment in Tegula funebralis (Adams 1854)

1. 1. Tegula funebralis regulates its internal osmotic concentrations of organic compounds in salinities from 100% to 160% sea water, but not in 50% sea water. 2. 2. Amino acids are used to help regulate internal osmotic pressure up to 120% sea water. Another ninhydrin-positive substance tends to replace amino acids in animals held in 160% sea water. 3. 3. Alanine, arginine, aspartic acid, glutamic acid, glycine and taurine are found in high concentration in this species. 4. 4. Uric acid levels tend to be higher in animals held in the higher salinities.

Studies on Selective Feeding in the Pacific Starfish Pisaster in Southern California

The asteriid starfish Pisaster giganteus and Pisaster ochraceus are important predators of mollusks. Experiments were designed to determine the extent to which predation by starfish on different kinds of prey is selective, and to learn whether selectivity varies according to 1) number and relative density of various alternative prey and 2) past history of feeding of the predators. Seven species of intertidal mollusks were used as prey. When alternatives were presented in equal abundance and in pairs, both species of starfish showed a significant preference for one alternative in all but one pairing. The hierarchy of preferences was well—defined and consistent among replicates. When seven species of prey were presented together in equal abundance, the preferences were of the same patter but were, in general, weaker than those exhibited when prey were presented in pairs. In all experiments, mussels were preferred over other mollusks; the strongest preferences were for Mytilus edulis and Mytilus califonianus over other alternatives. Where mussels (M. californianus) and snails (Tegula funebralis) were presented as alternative prey, changes in their relative densities had little effect on the preference for mussels. When the relative densities of two species of snails (T. funebralis and Acanthina spirata, neither preferred when in equal densities) was varied, a slight preference was shown for the more abundant form at one extreme density only. In this experiment individual starfish exposed to the same relative densities of alternative prey differed in the proportions of alternatives they chose. Starfish fed only on snails (T. funebralis) for 3 months showed an increased preference for these snails over chitons (Nuttalina californica) as well as a reduced preference for mussels; the latter preference reappeared strongly after only 1 week of exposure to both prey. The hypothesis that predators induce stability in prey populations is discussed. The experimental results indicate the importance of preferential feeding to this question. Models of selective feeding based on short—term changes in hunger and situation may be inappropriate when applied to cold—blooded predators. An alternative interpretation, based on learning and hunting behavior, is given for the changes in selectivity observed in these experiments.

UDPG-glycogen transglucosylase and a natural inhibitor in crustacean tissues

1. 1. UDPG-glycogen transglycosylase has been demonstrated in the major tissues of a crab ( Cancer magister) and in the muscles of crabs ( C. magister, Hemigrapsus nudus), a crayfish ( Astacus cambarus), molluskus ( Mytilus californianus Tegula funebralis), fishes ( Pomoxis annularis, Salmo gairdneri, Aequidens portalegrensis) and amphibians ( Rana pipiens, Bufo marinus). 2. 2. The crab muscle enzyme requires glucose-6-phosphate (glc-6-p) and has a pH optimum at 8·3. It is unstable in crude preparations, but is stabilized by addition of fluoride and glc-6-p. 3. 3. The enzyme activity is not associated with any specific sedimentable fraction in homogenates. 4. 4. Mixtures of homogenates of muscle with homogenates of hepatopancreas or eyestalk have an enzyme activity lower than predicted from the activities of homogenates assayed separately. The inhibitory effect of hepatopancreas homogenates is attributed to presence of hydrolytic enzymes, but the inhibitory effect of eyestalk extracts is attributed to a specific inhibitory factor. 5. 5. The inhibitory factor in eyestalk extracts is non-dialyzable; it is partly but not wholly destroyed by boiling, or treatment with 95 per cent alcohol or 1 N HNl in the cold. The factor is not soluble in ether. 6. 6. The inhibitory effect of eyestalk extracts varies with the stage of the donor in the intermolt cycle. 7. 7. Eyestalk extracts of crabs inhibit transglucosylase activity in muscle extracts from crabs, crayfis, mollusks and vertebrates. 8. 8. The possible relation of the inhibitory factor to the diabetogenic hormone of crustaceans, and to the control of carbohydrate metabolism, is discussed.

Carbohydrate digestion in a herbivorous snail. Tegula funebralis.

Carbohydrate digestion in a herbivorous snail. Tegula funebralis.

The Protozoan Fauna of Some Species of Intertidal Invertebrates in Southern California

This paper is chiefly a report of a survey conducted of the protozoan fauna of ten marine species of gastropods collected in the vicinity of the University of California at Los Angeles. The ten gastropod species belong in the groups commonly termed limpets and turbans, of the order PROSOBRANCHIATA, suborder SCUTIBRANCHIATA. The ten host species surveyed fall into two divisions: (1) Of the division DOCOGLOSSA, the species are Acmnaea pelta, A. digitalis, A. limatula, A. scabra, A. insessa, A. fenestrata fenestrata, and Lottia gigantea, all in the family ACMAEIDAE (the limpets), (Grant, 1938; Oldroyd, 1927). (2) Division RHIPIDOGLOSSA, subdivision ZYGOBRANCHIATA, Fissurella volcano (the volcano limpet), and subdivision AZYGOBRANCHIATA, Tegula funebralis, and T. ligulata, the black and speckled turbans, respectively, of the family TROCHIDAE (Oldroyd, 1927; Pratt, 1935). Eight hundred and fifty-nine animals in all were examined and their contents noted. Interest was primarily focused upon the ciliate population when it was found that it comprised the consistent bulk of the parasite faunules present within the host species. The ciliates were found to be of six different species. Four were species of the order PERITRICHA, Urceolaria karyolobia Hirshfield (1949), Urceolaria korschelti Zick (1928), Trichodina tegula Hirshfield (1949), of the family URCEOLARIIDAE, and Scyphidia ubiquita Hirshfield (1949), of the family SCYPHIDIIDAE. The morphology of Urceolaria karyolobia, Trichodina tegula, and Scyphidia ubiquita is described in another paper (Hirshfield, 1949). The fifth was a heterotrich of the family LICNOPHORIIDAE, Licnophora conklini Stevens (1904), and the sixth a thigmotrich of the family ANCISTRUMIDAE, Eupoterion pernix MacLennan and Connell (1931). This study is the report of the incidence of the above six ciliates within the ten host species and cross infection experiments conducted between the host species. COLLECTION SITES AND METHODS OF COLLECTION