Archive for February, 2012
Monday, February 27th, 2012
The Devonian period, some 350 million years ago, some of the crossopterygian fishes came out onto the land. It is very likely that these fishes were of a type represented by the genus Eustenopteron. In evolutionary terms, this was one of the boldest steps in history: a venturing of early vertebrates into a completely new environment to which they were only partially adapted. Once this step had been made, however, it was not long before these advanced, air-breathing fishes became transformed into primitive Amphibia.
From available fossil evidence it has been calculated that the earliest amphibians belonged to a group known as chthyostegids, creatures that had characteristics of both the crossopterygian fishes and the later, more advanced amphibians. A typical chthyostegid, a member of the genus Ichthyostega, had a skull about 15 cm (6 in) in lenght. Although similar in many respects to the skull of crossoptergian fish ancestor, there were certain important changes between that of the fish and that of the amphibian. In the fish, for example, the part of the skull in front of the eyes was comparatively short, while the portion behind the eyes was comparatively long. In Ichthyostega a paradoxical situation prevailed in which the portion of the skull behind the eyes was relatively shorter than that of the fishes and the portion in front relatively longer. In amphibians, the eyes tended to be oriented more toward the top of the skull than in the fishes. Although Ichthyostega had developed strong pectoral and pelvic girdles that carried completely developed limbs and feet, the fin rays of the fish tail were retained! From this early fish/amphibian we can follow the evolution of the later amphibians as they radiated into different lines.
In changing from a totally aquatic experience to a new terrestrial life, various problems had to be resolved. While a fish normally obtains its oxygen from water by means of gills, the early amphibians had to further develop and perfect the lungs that they had inherited from their crossopterygian ancestors, although in the larval stage (as is still the case with modern amphibians) they continued to respire by means of gills. Another problem that land-dwelling animals had to deal with was the possibility of desiccation or drying up.
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Tags: Air Breathing, Amphibia, Amphibian, Amphibians, Ancestor, Aquatic Experience, Creatures, Devonian Period, Evolutionary Terms, Fin Rays, Fish, Fish Tail, Fishes, Fossil Evidence, Genus, Million Years, Paradoxical Situation, Pelvic Girdles, Respects, Skull, Terrestrial Life, Vertebrates
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Tuesday, February 21st, 2012
Endeavoring to sort out the species into some kind of logical categorization. Fortunately, a system was developed that has solved the vast majority of the problems, this being known as the binomial system of scientific nomenclature, in which each distinct species (the most natural and basic group, consisting of individuals which are very similar and which freely interbreed) is awarded a double scientific name. The system was pioneered by the Swedish biologist Carl von Linne (1707-1778), generally known as Linnaeus. Basically, the system dictated that each species described to science should be given a generic and a specific name. As an example, the tiger salamander is known scientifically as Ambystoma tigrinum, the first name being that of the genus, the second that of the species. There are other species of the genus Ambystoma (Ambystoma macalatum, Ambystoma opacum, Ambystoma gracile, and so on), and all of these species show certain similarities of structure that warrant their being placed in the same genus.
Genera (plural of genus) are grouped into larger categories in ascending sequence: the family, the order, the class, and so on. To illustrate the situation more clearly, the following table shows the classification of a single species, the tiger salamander, Ambystoma tigrinum:
Kingdom: Animalia, all animals. Phylum: Chordata, all chordates, Subphylum: Vertebrata, all vertebrates. Superclass: Tetrapoda, limbed vertebrates. Class: Amphibia, all amphibians, Order: Caudata, salamanders. Family: Ambystomidae, more salamanders. Genus: Ambystoma, typical mole salamanders. Species: Ambystoma tigrinum, tiger salamander. Subspecies: A.t. tigrinum, eastern tiger salamander. Subspecies: A.t. californiense, California tiger salamander. Subspecies: A.t. melanostictum, blotched tiger salamander.
In the table, it will be seen that the basic species type is Ambystoma tigrinum. This species has been selected as an example due to the fact that it has many subspecies, a few of which are listed (there are no subspecies in many species). In cases where geographical races are different but not different enough to warrant separate specific rank.
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Tags: Ambystoma Tigrinum, Binomial Nomenclature, Binomial System, Blotched Tiger Salamander, California Tiger Salamander, Carl Von Linne, Class Amphibia, Distinct Species, Eastern Tiger Salamander, Genus Ambystoma, Gracile, Linnaeus, Mole Salamanders, Order Caudata, Salamander, Salamanders, Species Type, Subphylum Vertebrata, Tiger Salamander, Vertebrates
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Friday, February 17th, 2012
What’s in a name? This pair of Triturus vulgaris are readily recognized by the scientific name, but they are known by a variety of common names in different countries and languages. Americans call them European Common Newts.
An expert, a sub specific name is added to the binomial, thus making it a trinomial. In such cases, the first described population of the species becomes representative of species and has its specific name simply repeated thus: Ambystoma tigrinum tigrinum (or, more conveniently, A.t. tigrinum), while further races described will receive a different subspecific name (e.g., A.t. mavortium, etc.)Subspecies will freely interbreed with each other where their natural ranges overlap. They usually interbreed when brought together in captive conditions, but this has little to do with their status as species or subspecies. Hybrids resulting from intersubspecific matings are called intergrades and may resemble either of the parents, may possess characteristics of both, or may (very rarely) have a totally different appearance. Natural intergrades sometimes pose taxonomic problems for field researchers. The question of subspecies is a touchy one with many herpetologists, and beginners are best advised to try to ignore them if at all possible.
In normal literature the generic, specific, and subspecific names are universally italicized (or underlined in the absence of italic script). Most scientific names are derived from classical Latin or Greek, as these were the main languages used by learned scholars at the time of the inception of the binomial system. To the modern salamander fancier it may seem rather superflous.
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Tags: Binomial System, Captive Conditions, Classical Latin, Common Names, Dodge Grand Caravan, Field Researchers, Grand Caravan, Herpetologists, Learned Scholars, Maple Ridge, Matings, Natural Ranges, Newts, Salamander, Scientific Names, Subspecies, Taxonomic Problems, Trinomial, Triturus Vulgaris, Wedding Catering
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Monday, February 13th, 2012
The life history of the average frog is known by every school child, but for some unknown reason rather less seems to be known about the biology of the tailed amphibians. In this book we are not so concerned with the internal anatomy and physiology of the caudates as with their behavioral biology. In order to keep them alive in our terraria and encourage them to reproduce, it is most important that we know what makes them tick and what influences their breeding cycles.
Let us first endeavor to explain the differences between “salamanders” and “newts.” There is no hard and fast distinction between the two types, and species commonly called salamanders may even belong to the same family. The term salamander, however, may be safely applied to all of the caudates, while newt is normally applied to certain semi-aquatic species which live on land from late summer through winter but enter water in the spring to breed; male newts often have elaborate breeding dress and courtship behavior. In Europe the newts are represented most commonly by salamanders of the genus Triturus, in North America by members of the genera Notophthalmus and Taricha, and in Asia by Cynops, Paramesotriton, Tylototriton, and others.
The salamanders and newts of the order Caudata comprise some 350 species belonging to eight families. They are found in North and South America (with a preponderance of species in the north), in Europe and North Africa, and in Asia, predominantly in the north temperate zones. They are absent from tropical parts of Asia and Africa and do not occur at all in Australasia.
The salamanders have a soft, moist skin, rather long bodies, and well developed tails. As the body regions are distinct and the front and hind legs are usually of similar size and well developed, salamanders are often mistaken for lizards. However, on closer examination it will be seen that they lack the scaly skin, claws, and external ear openings of the lizards. All salamanders (sirens are partially herbivorous) and their larvae are carnivorous. The smaller species feed upon insects and other available invertebrates, but the largest ones can take any small vertebrate they can overpower, including fish, and frogs.
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Tags: Anatomy And Physiology, Anatomy Physiology, Aquatic Species, Behavioral Biology, Body Regions, Courtship Behavior, Distinction, Endeavor, External Ear Openings, Frog, Genus Triturus, Hind Legs, Internal Anatomy, Life History, Moist Skin, Newt, North Africa, Preponderance, Salamander, Salamanders, Salamanders And Newts, Scaly Skin, Tailed Amphibians, Temperate Zones, Terraria
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Thursday, February 9th, 2012
Triturus Cristatus is one of those species normally called a newt. Although it may be almost totally aquatic in some parts or its range, it is best known for entering breeding ponds in the spring after spending a period of hibernation in a deep cavity during the winter. The breeding season varies with the part of the range, but in central Europe the newts enter the breeding ponds in about mid-March.
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Tags: Cavity, Central Europe, Chichen Itza, Hibernation, Life History, Mexico, Mid March, Nbsp, Newt, Newts, Ponds, Puerto Morelos, Wedding Catering, Winnipeg
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Sunday, February 5th, 2012
Asian salamanders (Andrias) and the North American hellbender (Cryptobranchus), fertilization is internal, but is accomplished without copulation. A gelatinous pyramidal structure, the spermatophore is deposited by the male in a suitable spot. The spermatophore is capped by a packet of spermatozoa that is retrieved by the receptive female with her cloacal lips. The spermatophore dissolves in the body but the sperm are stored for later use. As the eggs are laid, they are fertilized by individual sperm. In most cases the eggs are laid in water (many plenthodontid species being exceptions to this), often attached individually to leaves of aquatic vegetation where they soon develop a protective jelly-like capsule. Some species “lay” free-swimming larvae that have developed within the female’s body; others produce small versions of the adults that may be born directly on the land. Many woodland salamander species do not lay their eggs in water, but deposit them in some suitable sheltered and damp cavity. The young that hatch from these terrestrial eggs bypass the larval stage and hatch as miniature replicas of the adults.
The larvae of water-breeding species are entirely carnivorous and start feeding upon tiny aquatic animals within hours of hatching. At first the larvae are similar to the tadpoles of frogs but possess more conspicuous feathery external gills on either side of the head. They do not develop the large head of the anuran larva, however, and the front limbs develop before the hind ones (hind before front in frogs). As examples, let us take a more detailed look at the life histories of two species, the great crested newt, Triturus cristatus, and the fire salamander, Salamandra salamandra.
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Tags: Andrias, Aquatic Animals, Chichen Itza, External Gills, Fire Salamander, Great Crested Newt, Hellbender, Larval Stage, Life Histories, Miniature Replicas, Puerto Morelos, Pyramidal Structure, Receptive Female, Salamander Species, Salamanders And Newts, Salamandra Salamandra, Spermatophore, Spermatozoa, Suitable Spot, Winnipeg Auto Dealers
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Wednesday, February 1st, 2012
By far the best type of tank available for general purposes is the all-glass tank. This consists of a number of sheets of glass of appropriate sizes cemented together along their edges with a remarkable versatile substance called silicone rubber sealing compound (silicone cement). This type of putty has various commercial uses, but brands suitable for aquarium construction are usually available at pet shops. All-glass aquaria are available in a wide array of sizes and designs at any pet shop, and it is usually cheaper to buy an all-glass tank than to try to make one yourself.
Great care should be taken in properly placing and aquarium for aquatic salamanders, remembering that a tank of water is extremely weighty. A sturdy base should be chosen and put in a quiet location away from a window and near an electrical outlet. Once in its permanent position, the tank should be thoroughly cleaned (without soaps) then filled with water and tested for leaks, which can be repaired with silicone cement.
Most of the smaller aquatic salamanders will appreciate a natural looking environment with plants, rocks and other decorative materials. Good tips on setting up a planted aquarium can be obtained from books about keeping tropical or cold-water fishes. Here it will suffice to say that a layer of washed aquarium gravel about 5 cm (2 in) deep at the front of the tank, rising to about 7.5 cm (3 in) at the rear, should be placed in the aquarium.
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Tags: Aquaria, Aquarium Construction, Aquarium Gravel, Chichen Itza, Cm 2, Cm 3, Cold Water, Decorative Materials, Electrical Outlet, Glass Tank, Pet Shop, Pet Shops, Puerto Morelos, Putty, Quiet Location, Salamanders, Setting Up A Planted Aquarium, Silicone Rubber, Sturdy Base, Winnipeg Auto Dealers
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