Cave Forms Research Articles

Comparative Ultrastructural Studies on the Pineal Organ of the Mexican CatfishRhamdia laticaudaHeckel, 1858 and One of its Cave-dwelling Derivates (Pimelodidae, Teleostei)

The pineal organ of the epigean catfish Rhamdia laticauda and of its cave-dwelling derivate from Cueva del Tunel in Zongolica, Mexico, was examined ultrastructurally. The pineal of the epigean form is relatively small but ultrastructurally well differentiated and characterized as a metabolically active, photoneuroendocrine organ. The outer segments of the sensory cells are composed of 32–55 very regularly arranged sacculi which are obviously functioning in photoreception. Furthermore, the presence of electron-dense vesicles, free ribosomes, conspicuously well-developed Golgi bodies, and large amounts of rough and smooth endoplasmic reticulum in the cytoplasm provide evidence for a secretory activity of the sensory cells. The only regressive traits in the pineal of the cave form regard the outer segments: there are few disintegrated, whorl-like outer segments and the number of sacculi exhibits an increased variability. Compared with other morphological structures dependent on light, for example the eyes, the degree of regression is very low. It is suggested that this is due to a remaining secretory role of the sensory cells, which prevents the functionless, photoreceptive outer segments from rapid degeneration by developmental constraints.

Die Feinstruktur der Kolbenzellen (Schreckstoffzellen) in der Epidermis von Astyanax mexicanus Filippi 1853 (Characinidae, Pisces) und seinen Höhlenderivaten “Anoptichthys”

AbstractFine Structure of the Club Cells (Alarm Substance Cells) in the Epidermis of Astyanax mexicanus Filippi 1853 (Characinidae, Pisces) and its Cave Forms “Anoptichthys”The club cells in the epidermis of Astyanax mexicanus are of the same ultrastructure as those in other Ostariophysan fish. There are also no essential differences to be found between the club cells of epigean Astyanax mexicanus and its cave forms “Anoptichthys”. Our findings correspond to former statements in that the function of the club cells producing and releasing alarm substances has been maintained in the cave forms.

Cave Colonization by Fish: Role of Bat Predation

Freshwater fishes found in a tropical pool regularly enter a subterranean source of water. They do so mostly when fishing bats are active in the evening. If fish are experimentally attracted to the pool during this period, fishing bat activity increases. Laboratory studies demonstrate that avoiding open areas in the evening is characteristic of these fishes. Predation by fishing bats can be a selective pressure favoring cave dwelling, an alternative hypothesis on the origin of cave colonization to entrapment and directional evolution. INTRODUCTION Although many examples exist of obligate (troglobitic) and facultative (troglophilic) cavernicoles for which a surface (epigean) ancestor can be presumed, the origin of cave colonization remains puzzling. Some theories of the evolution of cave populations assume accidental entry into caves followed by permanent entrapment of the organisms. Others propose some directional (regressive) evolution on the assumption that cavernicolous animals represent dying phylogenetic lines which seek refuge in caves (see Barr, 1968, for a review of these theories). Neither assumption has experimental confirmation. A ubiquitous freshwater teleost, Astyanax fasciatus mexicanus (Characidae), is frequently cited as an example of cave adaptation from an epigean ancestor. It is found as an eyed and pigmented surface form and as a blind and depigmented cave one. Although Hubbs and Innes (1936) described the cave form as a new genus and species (Anoptichthysjordani), breeding experiments (Peters and Peters, 1973; Sadoglu, 1957), as well as cytogenetic (Kirby et al., 1977) and electrophoretic studies (Avise and Selander, 1972), indicate that these two forms are conspecific. These forms differ not only in their morphology but also in their behavior. In contrast to the behavior of the eyed form, the blind one does not school, lacks periodic activity cycles (i.e., does not have rest periods like the epigean one), is not aggressive and, although it produces an alarm substance, does not react to it (Breder, 1943; Pfeiffer, 1966; Schemmel, 1980). Several species of tropical bats capture fish such as Astyanaxfasciatus from surface waters (Bloedel, 1955; Reeder and Norris, 1954). The echo-locating Noctilio leporinus, for example, is known to prey on A. fasciatus and on the cichlid Cichlasoma urophthalmus (Simmons et al., 1979; Suthers, 1967; Villa-R., 1966). The distributions of N. leporinus and A. fasciatus are very similar, the former ranging from central W Mexico to Argentina, the latter from southwestern USA to Argentina. At the beginning of the wet season (May) of 1982, I studied a two-species assemblage of about 120 fishes, ca. 60% Astyanax fasciatus and 40% the poeciliid, Brachyraphis rhabdophora. This assemblage colonized a shaded pool, fed by subterranean waters, that was constructed in 1976 close to La Hacienda de Palo Verde, Guanacaste Province, Costa Rica. Diurnal observations on these fishes suggested that both species show an affinity for the subterranean habitat, evidenced by their behavior and distribution. Both species carry food into the subterranean cavity prior to eating it (Romero, 1984). Casual observations indicated that fishes move into the subterranean source of water at dusk the time that fishing bats begin foraging (Bloedel, 1955)and that they reappear in the pool after the bats cease flying over it. METHODS AND RESULTS To examine whether the subterranean cavity serves to protect fish during the time

Influence of crystallization in microgravity conditions on the structure and magnetic properties of Gd 3Co and (Gd 0.2Tb 0.8) 3Co compounds

On board the orbital complex “Salyut-6” during long-term space flight, the experiment on crystallization of the rare earth-cobalt intermetallic compounds of the R 3Co type has been performed. The object of the experiment was to investigate the influence of microgravity on the macro- and microstructure and magnetic properties of Gd 3Co and (Gd 0.2Tb 0.8) 3Co compounds. The experiment included the melting in space of the compounds prepared on Earth under isothermal or thermal gradient conditions and crystallization during passive cooling. The change of meniscus form from the cave form which is characteristic of the ground-based samples to the concave form has been observed for the Gd 3Co flight samples. The Gd 3Co and (Gd 0.2Tb 0.8) 3Co flight samples were characterized with macro- and micropores of the sphere form. By means of vibrating magnetometer the temperature dependences of the magnetization have been measured in the temperature range of 4.2–300 K for Gd 3Co (at 1.7 kOe) and (Gd 0.2Tb 0.8) 3Co (at 500 0e) polyerystal ground-based and flight samples. The temperature dependences of magnetization of both compounds differ significantly compared to those for the ground-based samples in the temperature regions of magnetic ordering.

Etude comparative de la densite de groupes de poissons cavernicoles et epiges (characidae, cyprinidae, clariidae)

The group density of four species of cave fishes ( Caecobarbus geertsi, Barbopsis devecchii, Astyanax gen. and Uegitglanis zammaranoi) and of two taxonomically related epigean species ( Barbus conchonius and Hyphessobricon scholzei) was measured tridimensionally in an experimental aquarium, using a video recorder and a mirror inclined at 45° placed on top of the aquarium. The experiments were conducted in dim red light. The illumination was continuous in the case of cave fishes. For the epigean forms a 12/12 LD cycle was superimposed using dim achromatic sources. The relative positions of individuals within their own specific group were registered hourly during a week (168 h). Results show that in cave forms, the mean density of groups falls within the theoretical limits of random distribution values in all cases, whereas epigean species display a non-random aggregation tendency.

Exogenous and Endogenous Control of Swimming Activity in Astyanax mexicanus (Characidae, Pisces) by Direct Light Response and by a Circadian Oscillator II. Features of Time-Controlled Behaviour of a Cave Population and their Comparison to a Epigean Ancestral Form

Abstract 1. The swimming activity of 6 specimens of the Pachon cave form of Astyanax mexicanus was tested with regard to its time control under various light-dark(LD)cycles and constant conditions, and it is compared to that of a river form. 2. In general, activity is entrainable by all applied LDs, but even if the amplitude of a forcing signal increases the signal energies are lower than in the river fish. 3. In case of entrainment the maximum values of surface activity correspond to the dark phases, those of bottom activity to the light phases of a LD. Flexible patterns -as often observed in the river form in the range of resonance about 24 h - are very seldom. Furthermore, disturbances of­ ten occur in the entrainment of one activity form, or one form runs arrhythmic while the other is still entrained. 4. The activity answers to changing environmental conditions are not as uniformly quick as in the river fish. But the system hardly needs a swing-in time to become entrained when a LD starts. 5. After transition from LD to DD (= constant darkness) the entrained rhythms disappear immediately. 6. In no LD with a period length differing from 24 h a circadian rhythm can be observed in addition to the entrained frequency. 7. These results show that the passive system of the river form has developped into an extremely passive one being unable to oscillate and thus has become simplified during regressive evolution. Concerning the circadian oscillator of the epigean ancestor, it was also subjected to regression, but it has not been completely lost. After a LD with a period length about 24 h the circadian oscillator is able to act as a stable system, clearly shown by the freerunning circadian rhythms of surface activity. But out of this range the oscillator is unable to control activity. In DD after all other LDs activity patterns are arrhythmic.

Space solidification experiment on Gd 3Co compound

On board the orbital complex “Salyut 6” during longterm 0-gravity space flight crystallization of the polycrystal samples of the intermetallic compound Gd 3Co has been performed. The object of the present experiment was to investigate the effects of microgravity on the solidification process, final macro- and micro-structure and magnetic properties of antiferromagnetic Gd 3Co compound. The experiment included the melting of Gd 3Co under the isothermal or thermal gradient conditions followed by passive cooling. The change of meniscus form from the cave form which is characteristic of the ground-based samples to the concave form for the flight samples has been observed. The formation of the reaction layers has been found as a result of the mutual contact between liquid Gd 3Co and Ta-container in all samples investigated. The temperature dependences of the magnetization with Neel peaks have been observed for the ground-based and flight samples of Gd 3Co. Magnetization values of the flight samples were appreciably higher than those of the ground-based samples.

Terrestrial isopod crustaceans (Oniscoidea) from Mulu Caves, Sarawak, Borneo

Summary Six species, five new, of terrestrial isopods (Oniscoidea) are described and one is redescribed from Sarawak on the north coast of the island of Borneo. One new species is described in a new genus. They were collected in the Gunong Mulu National Park, mostly from caves, but no truly troglodytic or cave forms were collected. Twelve species from the island of Borneo are recorded in a table Species from the region have not been studied in any detail before, and this is the first attempt to make complete descriptions so the species can be more easily compared with other species from nearby regions.

Disturbance of underground wilderness in karst caves

Karst cave systems comprise very fragile ecosystems, each one of which is unique according to cave form and location. Any alteration to the form and/or to the atmosphere or the overlying surface and catchment area has repercussions throughout the ecosystem, which are detrimental to the cave to a greater or lesser degree. Four major types of disturbance are considered, and some implications for the successful management of the cavern environment are alluded to.

Fusaric acid in Parkinson's disease

<h3>Abstract</h3> Aggression is a complex behavior that is observed across the animal kingdom, and plays roles in resource acquisition, defense, and reproductive success. While there are many individual differences in propensity to be aggressive within and between populations, the mechanisms underlying differences in aggression between individuals in natural populations are not well understood. We addressed this using the Mexican tetra, <i>Astyanax mexicanus</i>, a powerful model organism to understand behavioral evolution. <i>A. mexicanus</i> exists in two forms: a river-dwelling surface form and multiple populations of a blind cave form. We characterized aggression in surface fish and cavefish in a resident/intruder assay through quantifying multiple behaviors occurring during social interactions. Surface fish, which are aggressive, display multiple social behaviors in this context, which we characterized into two types of behaviors: aggression- associated and escape-associated behaviors. The majority of these behaviors were reduced or lost in Pachón cavefish. Further, both aggression-associated and escape-associated behaviors were not dependent on the presence of light, and both surface fish and cavefish remained aggressive or non-aggressive, respectively, when opposed to fish from a different population. Additionally, we found that within populations, levels of stress response were not correlated with aggression- or escape-associated behaviors. Finally, when we compared aggression- and escape- associated behaviors across four cavefish populations, we found that both types of behaviors are reduced in three cave populations, while still present in one. Together, these results reveal that multiple cavefish populations have repeatedly evolved reduced aggression through shared behavioral components, while other cavefish have retained aggression. <h3>Summary Statement</h3> Comparison of aggression between surface fish and cavefish demonstrates that multiple complex behaviors compose aggression in surface fish and reveals heterogeneity in loss of aggression in cave populations.

Degenerative and constructive features of a phylogeneticcaly young cave form of Poecilia sphenops (Pisces, Poeciliidae)

AbstractDARWIN's statement, that rudimentary parts of organisms are apt to be highly variable, is also true for the regressive structures of cavernicolous animals. On the other hand, adaptive traits develop under cave conditions, the variability of which is lowered rather than increased, compared to that of their precursors in the epigean population. These differences in the genetically controlled variability of constructive and degenerative features indicate action and nonaction of natural selection.

GEOGRAPHICAL VARIATION AND EVOLUTION IN PSEUDOSINELLA VIOLENT A (FOLSOM).

For many years we have been studying the evolution of the cave forms of Collembola of the genus Pseudosinella. The first part of this study concerned the highly cave-adapted species, P. hirsuta, in the caves of the southeastern United States (Christiansen and Culver, 1968). The present work concerns P. violenta. This common species can be found throughout the United States and southern Canada as well as much of Latin America. It is primarily an inhabitant of the soil litter, particularly endogean regions such as abandoned ant nests and under stones. The collembola inhabiting such regions are generally quite different from cave forms (Vandel, 1964) although some intergradation between the populations of the two environments does exist. In this work the term forms should be considered to apply to such endogeic elements. Pseudosinella violenta is one of the commonest surface species in non-arid areas, but it is rarely found in caves, except in central Texas where it has invaded caves extensively. Here it has started to go through some of the evolutionary changes seen in more highly evolved cave species. Collections were made in over 60 caves of Central Texas, largely by James Reddell and other members of the Texas cave survey. It soon became apparent that any analysis of the changes occurring in this group would have to involve extensive comparisons with surface populations. Suitable collections were made in Iowa in 1966 and 1967, and in Texas during June of 1968 (see Fig. 1). Analyses of the populations from all regions were made using semi-

GEOGRAPHICAL VARIATION AND EVOLUTION IN PSEUDOSINELLA HIRSUTA.

Cave collembola furnish excellent material for the study of evolution. This is the result of the limited nature of geographical movement between caves and the limited selective pressure of cave life resulting in the persistence of primitive forms in caves. Early studies have established both the nature of large scale evolution in cave forms and the relationship between behavior and form in this process (Christiansen, 1961; 1965). All of these studies have dealt with large scale changes involving clearly separated forms. In order to examine the small scale changes which have occurred in the caves, the geographical variation of Pseudosinella hirsuta (Delamare) and P. violenta (Folsom) in caves was analyzed in detail. An additional study of surface population variation in P. violenta is in progress. Pseudosinella hirsuta is the most variable troglobitic form of the genus in North America. It has been found in caves of Kentucky, Tennessee, Alabama, Georgia, and Virginia (see Fig. 1). The variation is extensive, so that some forms superficially resemble P. argentea (Folsom) and others resemble P. christianseni (Salmon) with all gradations in between. The species is highly cave-adapted and apparently has undergone extensive evolution within caves. Pseudosinella violenta is a cave troglophile that has invaded extensively the caves of the Edwards Plateau and adjoining regions of Texas. It has reached neither the stability nor the adaptations of P. hirsuta. It is in the early phases of the second stage of cave adaptation, as described by Christiansen (1961). P. hirsuta is in the beginning of the third and final phase of cave adaptation. In this first publication of these studies we shall deal with the variations in P. hirsuta. Subsequent papers will analyze the variation in P. violenta.

The Neurosecretory System in the Head of the Blind Cave Crayfish Cambarus Setosus Faxon

The distribution of neurosecretory cells in the head of the blind cave crayfish, Cambarus setosus, was determined. The degen- erate eye in this blind crayfish also was described. The cuticle is thinner at the tip of the eyestalk than elsewhere, suggestive of the previous exist- ence of a cornea. The degenerate optic nerve does not originate in the disrupted hypodermis. A distinct basement membrane marks the proxi- mal border of the degenerate eye. The cuticle has distinct folds in the region of the degenerate eye, suggestive of an earlier facetting. The sinus gland is morphologically the same as that found in eyed cray- fishes. The lamina ganglionaris, medulla externa, and medulla interna show signs of degeneration, the former most of all. In 1890 Parker described the morphology of the degenerate eyes in the blind cave crayfishes Orconectes pellucidus and Cambarus setosus. Since 1890, however, no one has probed further into the structure of the eyestalks of blind crayfishes. The sinus gland, an im- portant neurohemal organ in higher crustaceans with well-developed eyes, has not been described from blind crayfishes. Hanstr6m (1933, 1937), who discovered the sinus gland, described its structure from a wide variety of crustaceans including an eyed crayfish. However, blind cave forms were unavailable to him. Since the early 1950's interest in crustacean neurosecretion has been very high. In spite of this fact, neurosecretion in blind hypogeal species has not been the subject of even one investigation. The distribution of neurosecretory cells in the supraesophageal ganglia of eyed crayfishes has been re- ported by Durand (1956) for Orconectes virilis and by Fingerman and Aoto (1959) for the dwarf crayfish, Cambarellus shufeldti. In a

A Preliminary Survey of the Knowledge of North American Cave Collembola

At the present time virtually nothing has been published concerning the cave collembolans of North America. As simple proof of this, a bibliography of North American cave Collembola contains less than 30 entries, most of which are antiquated or mere listings of one or two erroneously identified species in a cave fauna of Blank Cave. The only general survey is that of Packard (1888) which encompassed less than one percent of the actual fauna and, from a taxonomic viewpoint, is either useless or seriously damaging. In addition to the work of Packard, various forms were described by Banks (1897). The accuracy of these descriptions can be measured if we consider that they were made generally with the use of a hand lens upon specimens often less than a millimeter in total size. The only adequate works devoted solely to North American cave forms are those of Denis (1929) upon Oregon material collected by Silvestri, of Delamare Deboutteville (1949) upon material from a few caves in Alabama and Tennessee collected by Henrot, and of Bonet (1934) upon material largely from a few Kentucky and Virginia caves. All of these works were published in European journals and are in French. In addition, several authors (Mills 1934, 1948, Bonet 1943, Wray 1952, and Christiansen 1958) have described single cave species from the United States in larger works concerned with other groupings. It is not possible to obtain a view of the cave Collembola fauna of the United States from this bibliography; however, work now in press, or in progress, will greatly increase our records in the genera Sinella (Christiansen, 1960) and Pseudosinella (in preparation). Much of the cave area of the United States is still virtually untouched from the standpoint of collembolans, and experience has shown that the simple statement that collembola is no indication of the presence or absence of these animals. In personal experience Collembola have been found in about two-thirds of the caves previously indicated to have none. Even the most astute collector may pass up these minute forms without experience and exhaustive search, or use of berlese extraction. At the present moment only the southeastern quadrant of the country has relatively complete collections, but examination of these, combined with the spotty collections from other parts of the country permits a rough guess as to the probable composition of the fauna. The following genera are known to occur in American caves

Dispersal of Cavernicolous Beetles

IN North American caves there live beetles of several families, such as the Pselaphidae, Staphylinidae, Catopidae, and Carabidae. In the subfamily Trechinae of the last mentioned family five genera are known (Pseudanophthalmus, Neaphaenops, Ameroduvalius, Darlingtonea, and Nelsonites) which live in caves and are highly modified. Specifically they are generally eyeless, wingless, and depigmented, and possess attenuate legs, antennae, and setae. Beetles of these genera, commonly referred to as anophthalmids, are considered true cave forms. One genus, Pseudanophthalmus, is by far the most abundant and widespread. Largely on the basis of excellent work by Valentine and Jeannel in the past few decades, this genus is now known to consist of almost a hundred described forms from six states. This report will be based on forms of this genus. There is no record of Pseudanophthalmus ever having been taken outside a cave. Thus it might seem strange at first glance that information relative to insect dispersal might come from a study of this genus. Yet these forms are of great interest, and especially with respect to dispersal, just because they are restricted to caves. Populations isolated in caves have in many cases accumulated distinctive characteristics, particularly in aedeagal structures, on the basis of which they are describable as distinct forms. But, in addition, the forms, within a given area are generally found to be more closely related to one another than to forms from a distant area. This would seem to indicate that one or several things have happened. At one extreme it could be that tre-

The carotenoid pigments of some amphipod crustacea.

ABSTRACT The visible coloration of three species of amphipod Crustacea (Gammarus pulex, G. marinus and Orchestia gammarella) was found to be due almost exclusively to carotenoid pigments, including in each case a proportion of an astacin-like carotenoid acid. No carotenoid pigments could be demonstrated, even in traces, in three species of the cavernicolous Amphipod genus Niphargus. Carotenoid pigmentation is thought to be characteristic of Amphipoda and would therefore be the ancestral pigment of the cave forms. The lack of pigment in cave Amphipoda may be due to absence of light; it is not due to lack of carotenoid pigments in the food.

Notes on an American Cave Flatworm, Sphalloplana Percaeca (Packard)

EcologyVolume 17, Issue 2 p. 194-211 Article Notes on an American Cave Flatworm, Sphalloplana Percaeca (Packard) J. William Buchanan, J. William BuchananSearch for more papers by this author J. William Buchanan, J. William BuchananSearch for more papers by this author First published: 01 April 1936 https://doi.org/10.2307/1931459Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume17, Issue2April 1936Pages 194-211 RelatedInformation

Experiments on the light and tactile reactions of a cave variety and an open water variety of an amphipod species

The amphipod, Eucrangonyx gracilis (Smith), occurs in the waters of many caves in southern Indiana and is very generally and abundantly distributed in small surface streams in the same region. The individuals occurring in caves almost without exception have very little or no body pigment though possessed of the normal pigment in the eyes. Those living in surface streams have the usual amount of pigment for a crustacean. In other structural characters the forms are apparently alike.In an attempt to determine whether there was a physiological difference between the two forms they were tested for light and tactile reactions. These amphipods are negative to all intensities of light to which they respond. Extended series of light experiments using horizontal illumination were conducted during which every effort was made to maintain as precise conditions as possible. The cave form was found to be somewhat less responsive to light than the form living outside caves, but this difference was not large and was dist...

The Inheritance of Acquired Characters

IN reviewing Prof. Eigenmann's book on the cave vertebrates of America (NATURE, November 11, p. 40), the reviewer quotes the author's opinion that “The bleached condition of animals living in the dark, an individual environmental adaptation, is transmissible, and. finally becomes hereditarily fixed.... Natural selection cannot have affected the coloration of the cave forms, for it can be of no consequence whether a cave species is white or black”. Your reviewer further dismisses Romanes's supposition that colour may be correlated, with other structures which are subject to selection.