Mercoledì Nov 22

Vertebrates 1

The zoology exhibits begin with vertebrates. Please note that none of the animals on display were killed for the sole purpose of being exhibited here. While it is undoubtedly useful to see these species close up, this cannot justify the deaths of living beings. You will notice that the various animals are identified both by their common and scientific names, accompanied by information on their position within the animal kingdom, and on their range, or geographic distribution. Where applicable, it is specified whether they are endangered species, and protected in accordance with the Washington convention. Indications are also given as to whether they can be legally hunted in Italy or not. The panel with the blue background highlights one of the distinctive features of fish, amphibians, reptiles, birds and mammals – the backbone. The cabinet immediately to the left contains casts of fossils representing each of the five groups of vertebrates. The tactile area, opposite, provides visitors with an opportunity to touch the characteristic integuments of the various vertebrate classes: shark skin, the scales of fish, the plates of the crocodile, the bird’s plumage, and rabbit fur. The panel to the right features the mobile reconstructed spinal column of a nandu (a large South American bird). It shows us just how perfectly vertebrae are linked the one to the other to ensure support and movement. The nandu’s leg specimen illustrates limb structure.

The room dedicated to fish provides three approaches to these species. One part, to the left, deals with the biological and ecological characteristics of the group, and with Cyclostomata, the vertebrates surviving to this day endowed with the most primitive characteristics. Fossil remains of the Cyclostomata can be dated back to more than 300 million years ago. The area opposite the entrance is entirely given over to Chondrichthyes, i.e. fish with a cartilaginous skeleton). The cabinets feature plaster reconstructions of sharks, cramp fish and rays. The belly of the ray exhibited on the wall clearly features the fish’s branchial clefts. On the back of the ray, to the back of the cabinet, we find two apertures termed opercula. Rays have adapted to life on the sea bed. Thus, to avoid also taking sediments into their respiratory apparatus, they take water in from apertures on their back. Following gaseous exchange, the water leaves the fish via the ventral branchial apparatus. To the right, two cabinets illustrate Osteichthyes, i.e. fish with a bony skeleton. The approximately 20,000 species of bony fish discovered to date colonise all freshwater and marine habitats. Here we find specimens reconstructed in plaster, and other specimens prepared with the skin. The moray is a sure favourite with visitors. Its markedly pointed teeth clearly tell us this is a predatory species. The rhombus, a flatfish with both eyes positioned on its back, and two globe-fish are also displayed. One specimen is round, which is the typical form assumed by the globe-fish when threatened, and the other is flatter, which is the form assumed by the globe-fish when swimming in normal conditions. The aquarium on the back wall, with freshwater species, illustrates how fish move, feed and breathe. We also come to learn of the typical similarities and differences between various species. On the wall toward the fish room exit, we find a reconstructed latimeria. This fish belongs to a group thought to have died out more than 60 million years ago – until 1938, when a specimen was fished out of the sea off the coast of South Africa, offshore from the Chalumna river. More than 150 sightings have been made since then. Study of the latimeria sheds light on certain characteristics of these primitive beings, such as trilobate tail and fins supported by a muscular base which includes articulated bones.

Cabinets on the left of the corridor feature amphibians, whose name means dual life. To prevent dehydration of the egg, most species lay their shell-less eggs either under the water or in very damp places. The resulting larvae have fish-like bodies, and breathe through gills. They then change dramatically to become, in their adult form, four-legged creatures. They can then live on the land and breathe through lungs. Amphibians include frogs, toads, salamanders and newts, species all living in the vicinity of fresh water. The examples on display include the yellow-bellied toad. This toad, which loves muddy water, is a diurnal species. If threatened, it exposes its brightly coloured belly, which potential predators take as a warning. The two salamanders are also of interest. One is a pied salamander, with orange spots on a black background. The species is to be found practically throughout Italy. The other salamander, completely black, lives mainly at altitudes of over 600 metres in the Alpine arc to the east of Lake Como. The two species differ also in the manner in which they reproduce. The pied salamander reproduces in the manner of all other amphibians. The black salamander, on the other hand, gives birth to offspring already formed within the mother’s belly. The gills regress before birth, which means that birth can also take place away from water.

The area dedicated to reptiles starts with a panel illustrates the basic characteristics of this group. One curious snake-like species is the slow-worm, or blind-worm, whose habits have deprived it of limbs. The large central cabinet is entirely dedicated to turtles and tortoises. The Caretta caretta turtle skeleton illustrates the specific structure of these reptiles. The elements consist in carapace, spinal column, skull and limbs. To ensure suitability for their aquatic or terrestrial habitats, the forms assumed by the various species will clearly differ. The green turtle – present also in the Mediterranean – has a hydrodynamically formed carapace, which flattens out to the back, and flipper form legs. The Egyptian tortoise, whose habits are not entirely aquatic, features strongly clawed feet and a rounder carapace. Land tortoises, such as Testudo hermanni, are a characteristic feature of our fauna, with their domed carapace and strongly clawed perpendicular legs. Two cabinets are dedicated to snakes. The form of the two splendid Boa constrictors is perfectly recognisable as belonging to the snake. Boa constrictors kill by wrapping themselves around their prey and squeezing the breath out of them. The striking colour of the highly venomous coral snake means but one thing – danger. The next cabinet features specimens conserved in alcohol and reproductions. These are local species from our own province. Here, a clear distinction can be made between harmless grass snakes, such as the coluber and natrix, and the more dangerous viper. Another snake – most definitely not a typical representative our local fauna – is the Gaboon viper. Noteworthy also because of its striking appearance, it is the largest and most dangerous of all vipers. Our look at reptiles ends with two truly spectacular exhibits, the American alligator and the Nile crocodile. The centrally positioned conserved skeleton gives us a general idea of the anatomy of alligators. The manner in which the skulls are displayed allows us to note the distinctive characteristics of the three existing groups of crocodiles, also thanks to the mirror placed above them.

There are nearly 10,000 bird species worldwide. Throughout mankind’s history, birds have been very much a part of our lives (farming, pets, hunting, bird watching). Consequently, this is the most extensively studied of all groups of animals. A key feature of this species is its mobility. Here, we see the geographic distribution of bird species. Red, yellow and blue indicate sedentary or non-migratory, nesting and wintering birds, respectively. Some cabinets present species which have adapted to aquatic environments. Very many species are to be found in coastal areas, on riverbanks and in marshland areas, where they nest, raise their young and feed. To adapt to their environments, some species have developed long legs, as can be clearly seen in the cases of the stilt-plover and ruff. Webbed feet, as in ducks and geese, are another form of adaptation. We should also note the form of the long, curved beak of the glossy ibis, ideal for scavenging for insects among the stones. Many species clearly presenting sexual dimorphism are featured. Sexual dimorphism is when marked differences in appearance occur between the males and females of a given species, such as we note in the widgeon, the great crested grebe and the garrot. The painted backdrop illustrates the typical flying formations of some of the species displayed in the cabinets.

Some cabinets host a number of typical rocky coastline species, such as stormy petrels – which live on the open sea under all weather conditions and approach the coastline only to nest –, or cormorants, which capture fish by diving into the water, and propelling themselves with their feet and half-open wings even to a depth of 10 metres.  A number of highland species of terrestrial habits are featured, such as the rock ptarmigan, in two exhibits, presenting the bird’s summer habitus and the winter habitus. The capercaillie is a clear example of sexual dimorphism. The capercaillie is represented here by two males and a female. The ptarmigan and capercaillie are local birds, but they are very rare, and their populations are declining rapidly. The central area of the room is entirely given over to daytime predators. Here, we note in particular three splendid bearded vulture specimens and a golden eagle. Up to 1977, birds of prey were considered harmful to the interests of their human neighbours. They could therefore be freely hunted down. Nowadays, they are protected by law, with severe penalties for persons discovered killing these birds. A number of couples of eagles – frequently sighted on the wing – are to be found nesting regularly in the Alpine foothills of the Bergamo area. A Cabinet presents a number of nocturnal predators, including the Eurasian pigmy owl and the majestic eagle owl. Plumage fully protects these birds against the very low temperatures of the night, when they hunt. With their eyes to the front, these birds are endowed with stereoscopic sight. Their large eyes are also well suited to darkness. We can find a reconstruction of the manner of predation of the kingfisher, and the many forms and colours of the woodpecker. Please note the woodpecker’s nest, positioned inside the trunk of a birch.

Some cabinets highlight certain features of birds in general: the wing structure and plumage, the many forms and colours of eggs, and various nest types. The most original of the nests must be that of the penduline tit, a small passerine inhabiting areas near watercourses. Their bottle-shaped nests hang from the branches which are intertwined and held together with a cotton-like material which these birds obtains from inflorescences. The corner of the room is dedicated to ratites, also known as runners, i.e. the ostrich, the nandu and the cassowary. The claws of these long-legged birds are very powerful. Their wings are small, and their coat is made up of down alone. No longer capable of flight, their main line of defence against predators is their speed as sprinters. Ostriches can reach a top speed of about 70 km. per hour. The passerines are the species which we are probably most familiar with, since among them we find most of the birds which have adapted to the conditions of an urban environment as habitat. We should not forget another characteristic of birds. They sing. An interactive installation called “Listen to who’s singing” reproduces the songs of the most common species. Just press the big button in the middle and try to match the song and the bird that’s singing it!

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