Life Cycle of European Eel

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How many kilometers do European eels travel to reach their spawning grounds in the Western Atlantic Ocean?

2,000 to 3,000 km

1,000 to 2,000 km

5,000 to 6,000 km

3,000 to 4,000 km (correct)

At what depth do European eels spawn in the Western Atlantic Ocean?

500-600 meters

200-300 meters

100-200 meters

400-500 meters (correct)

What is the characteristic of the leptocephalus larva of the European eel?

It has a hard, armored shell.

It has a big, toothy mouth.

It has a long, snake-like body.

It is transparent and has large eyes. (correct)

How long does it take for the leptocephalus larva to reach its home in the river?

3 years Signup and view all the answers

What is the name of the second type of larva in the European eel's life cycle?

Elver Signup and view all the answers

How do the elver larvae migrate upstream to reach their home in the river?

They rely on drift and are swept by the current. Signup and view all the answers

What is believed to be the reason why some Swallows in North America changed their migration route?

They found a shorter route to similar habitats with less competition. Signup and view all the answers

What triggers physiological changes in birds that lead to migration?

Hormonal changes in the gonads Signup and view all the answers

What is the name of the hypothesis that suggests thyroid glands regulate the metabolic activities of birds, leading to migration?

The Thyroid Hypothesis Signup and view all the answers

What type of migration occurs when only a few members of a species participate in migration?

Partial Migration Signup and view all the answers

What is deposited in a bird's body before migration, stimulating the bird to migrate?

Fat Signup and view all the answers

How many types of bird migration are recognized?

12 Signup and view all the answers

What is the main reason why willow warblers migrate from Central and Southern Africa to northern Europe and Asia?

To take advantage of the abundant insect food available in northern Europe and Asia Signup and view all the answers

What is an advantage of breeding in the Arctic for birds such as Bewick's swans?

The longer day length allows them to feed for more hours Signup and view all the answers

Why do dotterels migrate to the tops of the highest Scottish mountains?

To nest on the high tops and avoid competition from other plovers Signup and view all the answers

What is a common reason why birds migrate to certain places year after year?

Because certain places are ideal for nesting Signup and view all the answers

What happens to the forests of northern Europe and Asia during the winter?

They become cold and dark, and insects are hard to find Signup and view all the answers

What is a characteristic of the Arctic during the summer?

There are almost 24 hours of daylight Signup and view all the answers

What percentage of Indian bird species are migratory?

20% Signup and view all the answers

Where do Koel birds emigrate to in the winter season?

Southern India and Sri Lanka Signup and view all the answers

What type of migration is seen in Snowy owls?

Cyclic migration Signup and view all the answers

What are birds like Sandpipers and Great snipes called?

Birds of passage Signup and view all the answers

When do Nee/kants emigrate from Himalayan range to plains of India?

In spring season (March/April) Signup and view all the answers

Which birds remain present in plains of India in spring season (March/April)?

Shoveller, Teal and Red Crested Pochard Signup and view all the answers

What is the approximate distance traveled by the Rosy Paster from Eastern Europe to Central Asia?

3,000 kms Signup and view all the answers

At what altitude do some species of birds, such as the Siberian crane, migrate?

Above 5,000 meters Signup and view all the answers

What is a characteristic of migratory birds in terms of their time of journey?

They are very punctual Signup and view all the answers

Where do some migratory birds, such as swallows, return to every year?

The same village and even the same tree Signup and view all the answers

What is a characteristic of the routes taken by migratory birds?

They are definite and follow a specific path Signup and view all the answers

What type of route do marine birds adopt?

Sea routes Signup and view all the answers