Ducks
The overall body plan of ducks is elongated and broad, and they are also relatively long-necked, albeit not as long-necked as the geese
and swans. The body shape
of diving ducks varies somewhat from this in being more
rounded. The bill is usually broad and contains serrated
pectens, which are particularly well defined in the
filter-feeding species.
This moult typically precedes migration.The drakes of
northern species often have extravagant plumage, but that
is moulted in summer to give a more female-like appearance,
"eclipse" plumage. Southern resident species typically show
less sexual dimorphism, although there are exceptions such as
the paradise shelduck of New Zealand, which is both strikingly
sexually dimorphic and in which the female's plumage is
brighter than that of the male. The plumage of juvenile birds
generally resembles that of the female. Over the course of
evolution, female ducks have evolved to have a corkscrew shaped
vagina to prevent rape.
Zdroj: Wikipedie
subarctic regions, but the greatest
concentration of species diversity is in tropical rainforest.
Frogs account for around 88% of extant amphibian species.
They are also one of the five most diverse vertebrate orders.
Warty frog species tend to be called toads, but the distinction
between frogs and toads is informal, not from taxonomy or
evolutionary history. An adult frog has a stout body, protruding
eyes, anteriorly-attached tongue, limbs folded underneath, and no
tail (the tail of tailed frogs is an extension of the male cloaca).
Frogs have glandular skin, with secretions ranging from distasteful
to toxic.