Earths magnetic field helps protect Earth and its organisms. It protects us from harmful particles given off by the sun. Most of the particles are attracted to the north and south magnetic poles. This is where Earths magnetic field is strongest. This is also where relatively few organisms live. Another benefit of Earths magnetic field is its use for navigation. People use compasses to detect Earths magnetic north pole. Knowing this helps them tell direction. Many animals have natural 'compasses' that work just as well. Birds like the garden warbler in Figure 1.36 use Earths magnetic field. They use it to guide their annual migrations. Recent research suggests that warblers and other migrating birds have structures in their eyes. These structures let them see Earths magnetic field as a visual pattern.

What do birds use to help in migration?

The dermis is the inner layer of skin. The dermis has blood vessels and nerve endings. The nerve endings explain why your skin is sensitive. You can sense pain, pressure, and temperature. You cut your finger and it starts to bleed. What has happened? If your skin bleeds, it means you have cut the dermis layer and damaged blood vessels. The cut really hurts. It hurts because of the nerve endings in this skin layer. The dermis also contains hair follicles and two types of glands. Hair follicles are structures where hairs originate. Each hair grows out of a follicle. Hair passes up through the epidermis. It then extends above the skin surface. Oil glands produce an oily substance. The oil is secreted into hair follicles.

The inner layer of skin which has blood vessels and nerve endings is called?

(CNN) -- English club Chelsea have completed the signing of Oriol Romeu from Spanish and European champions Barcelona. The 19-year-old is currently playing for Spain at the World Under-20 Championships in Colombia and has signed a four-year deal with last season's Premier League runners-up. The deal is worth $7 million and includes a buy back clause, set at $14 million after the first year and $21 million after the second. Romeu started his career at Barcelona's city rivals Espanyol before joining the Camp Nou academy in 2004. The midfielder, who can also play in central defence, made his debut for Barcelona in last season's Spanish Supercup match with Seville and got his first taste of league action against Deportivo in May 2010. He has played 90 minutes in both of Spain's games at the World Under-20 Championships, when they beat Costa Rica and Ecuador. Chelsea official web site confirmed the signing and said Romeu is "renowned for his strength and his expansive passing ability." Another player leaving Barcelona is Jeffren Suarez after he agreed to join Sporting Lisbon. The Portuguese outfit have paid $5 million for the 23-year-old which, like the Romeu deal, includes a buy back option. Jeffren joined Barca from Tenerife in 2004 and made his debut for the Catalan club in the 2006-07 season.
How old is Oriol Romeu?