source: https://www.bloomberg.com/news/articles/2019-04-24/major-emperor-penguin-breeding-ground-gone-barren-since-2016
Penguins
are a group of birds that cannot fly, but can swim. most of them live in
the southern hemisphere, with only one species, the Galapagos penguin.
After long adapting to
life in the water, penguins have countershaded dark and white plumage,
and their wings have evolved into flippers. They spend about half their
lives on land and the other half at sea
1. Scientific classificatione
- Size
The emperor
penguin is the largest of all living penguins, standing to 1.1 m (3.7
ft.) tall and can weigh more than 41 kg (90 lbs.).
The
smallest of the penguins is the little penguin, standing just 41 to 45
cm (16 to 18 in.) and weighing about 1 kg (2.2 lbs.).
- Body Shape
A Penguin has a large head, short neck, and elongated body.
The tail is short, stiff, and wedge-shaped.
The legs and webbed feet are set far back on the body, which gives penguins their upright posture on land.
- Flippers
Wings are
modified into paddle-like flippers. The bones are flattened and
broadened, with the joint of the elbow and wrist almost fused. This
forms a tapered, flat flipper for swimming.
Each
flipper is covered with short, scale-like feathers. The long wing
feathers typical of most birds would be too flexible for swimming
through water.
Instead of having wings like other birds, penguins have tapered, flattened flippers for swimming.
Penguins propel themselves through the water by flapping their flippers.
- Head
Different species of penguins can be identified by their head and facial markings. Penguins have a variety of bill shapes.
-
Generally, the bill tends to be long and thin in species that are
primarily fish eaters, and shorter and stouter in those that mainly eat
krill.
- The mouth is lined with horny, rear-directed spines to aid in swallowing live prey.
Eyes.
- The color of irises varies among the species.
- Many species have brown, reddish-brown, or golden-brown eyes.
- Rockhopper and macaroni penguins have red eyes.
- Fairy (little blue) penguins have bluish-gray eyes.
- As their name implies, yellow-eyed penguins have yellow eyes.
- Nearly all birds studied have circular pupils.
- Legs and Feet
Penguin legs are short and strong. Feet are webbed,
with visible claws. The legs are set far back on the body to aid in
streamlining and steering while swimming. This placement also causes
penguins to stand vertically and walk upright.
Penguins walk with short steps or hops, sometimes using their bills or tails to assist themselves on steep climbs.
Emperor and king penguins walk slowly and do not hop.
Some species, like the rockhopper penguins, jump from rock to rock.
- Tail
A penguin's
tail is short, and wedge-shaped, with 14 to 18 stiff tail feathers.
Adélie, gentoo, and chinstrap penguins (collectively known as
brush-tailed penguins) have longer tail feathers, which they often use
as a prop when on land.
- Feathers
Shiny
feathers uniformly overlap to cover a penguin's skin. Penguin feathers
are highly specialized. They are short, broad, and closely spaced. This
helps keep water away from the skin. Tufts of down on the feather shafts
increase the insulative properties of the feathers.
Penguins have more feathers than most other birds, with about 100 feathers per square inch.
- Coloration
All adult
penguins are countershaded: dark on the dorsal (back) surface and white
on the ventral (underside) surface. The dark dorsal side blends in with
the dark ocean depths when viewed from above. The light ventral side
blends in with the lighter surface of the sea when viewed from below.
The result is that predators or prey do not see a contrast between the
countershaded penguin and the environment.
Many species have distinct markings and coloration.
- Sexual dimorphism
Generally,
penguins are not sexually dimorphic: males and females look alike.
Crested penguins are exceptions: the males are more robust and have
larger bills than females.
When seen
in pairs during breeding season, royal penguins are one of the easiest
penguins species to visually identify males from females. Males have
larger bills and white cheeks while females often have gray colored
cheeks.
3. Habitat
Penguins generally live on islands and remote continental regions free
from land predators, where their inability to fly is not detrimental to
their survival.
These highly specialized marine birds are adapted to living at sea —
some species spend months at a time at sea. Penguins are usually found
near nutrient-rich, cold-water currents that provide an abundant supply
of food.
4. Types of Penguins
There are several types of penguins, including
- King penguins, Aptenodytes patagonicus
- Emperor penguins, Aptenodytes forsteri
- Adelied Penguins, Pygoscelis adeliae
- Rockhopper penguins, Eudyptes chrysocome
- White flippered penguins, Eudyptula albosignata
- Africa penguins (Jackass penguins), Spheniscus demersus
- Galapagos penguins, Spheniscus mendiculus
5. Food preferences and resources
Penguins eat krill (a shrimp-like
crustacean in the family Euphausiidae), squids, and fishes. Various
species of penguins have slightly different food preferences, which
reduce competition among species.
The smaller penguin species of the
Antarctic and the subantarctic primarily feed on krill and squids.
Species found farther north tend to eat fishes.
6. Life cycle
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