Which of the following whale species has a long external tusk?

a.
sperm whale

b.
narwhal

c.
beluga whale

d.
bowhead whale

e.
blue whale

Answer: B.  narwhal

The narwhal is the whale species that has a long external tusk protruding from a canine tooth. However, the function of this strange structure has remain a mystery for a long time, recent drone footage may have found the answer.  

Although it is believed that this 3 meter tooth may play an important role in mating, another function for it may be in hunting fish. In the footage, the individual uses it to hit the fish and thus stun it.

Furthermore, another function may also be echolocation, through which marine species, especially dolphins, use sound waves to "see" underwater.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.

starchy vegetables are high in carbohydrates.

starchy vegetables contain more carbohydrates than non-starchy vegetables.

explanation:

there are two primary categories of carbohydrates, essentially differentiated on the basis of their carbohydrate content (which is in the form of starch - a complex carbohydrate):

those vegetables which contain little amounts of starch are termed as non-starchy vegetables, and some examples include: artichokes, broccoli and bean sprouts.

vegetables high in their starch content are distinguished as starchy vegetables, and some examples include: potatoes, chickpeas and corn.