Directions: Read the excerpt from Stephen Leatherwood’s, David Caldwell’s and Howard Winn’s “Whales, Dolphins, and Porpoises of the Western North Atlantic.” Then answer the questions.

All five species of large whales with a dorsal fin belong to the same major baleen whale group, the balaenopterid whales or rorquals. All are characterized by the presence of a series of ventral grooves usually visible on stranded specimens and the length and number of which are diagnostic to species. In addition, all species, with the exception of the humpback whale, have at least one distinctive (though often not prominent) ridge along the head from just in front of the blowhole to near the tip of the snout. (The humpback whale, on the other hand, is distinguished by numerous knobs, some of which are located along the line of the head ridge with others scattered on the top of the head.) In Bryde's whale, the single head ridge characteristic of the other rorquals is supplemented by two auxiliary ridges one on each side of the main ridge.

At sea, these whales often appear very similar and must be examined carefully before they can be reliably identified.

In general, though the characteristics of behavior may vary from one encounter to the next, based on the activities in which the animal is engaged. Whales in this group may be distinguished from each other on the basis of differences in 1) the size, shape, and position of the dorsal fin and the timing of its appearance on the surface relative to the animal's blow (in general, the larger the whale, the smaller the dorsal fin—the further back its position and the later its appearance on the surface after the animal's blow); 2) the height of body in the area of the dorsal fin, relative to the size of the dorsal fin, which is exposed as the animal sounds; 3) sometimes the blow rate and movement patterns; and 4) the shape and color of the head.

Despite variability in behavior by members of the same species from one encounter to the next, an observer can greatly increase the reliability of his identification by forming the habit of working systematically through a set of characteristics for the species rather than depending on any single characteristic.

There are three species of large whales without a dorsal fin in the western North Atlantic Ocean. Two of these, the bowhead or Greenland whale, and its more widely distributed close relative, the right whale, are baleen whales. The third, the sperm whale, is a toothed whale. The first two have relatively smooth backs without even a trace of a dorsal fin. The sperm whale has a humplike low, thick, dorsal ridge, which from certain views particularly when the animal is humping up to begin a dive may be clearly visible and looks like a fin. But because the profile of that hump and the knuckles which follow it are often not very prominent in this species, it has been classified with the finless big whales.

All three species are characterized by very distinctive blows or spouts. In both the bowhead and the right whales, the projection of the blow upward from two widely separated blowholes assumes a very wide V-shape with two distinct columns, which may be seen when the animals are viewed from front or back. Though this character may be visible under ideal conditions in many of the other baleen whales species as well, it is exaggerated and uniformly distinct in the bowhead and right whales and may be used as one of the primary key characters. In the sperm whale, the blow emanates from a blowhole which is displaced to the left of the head near the front and projects obliquely forward to the animal's left. This blow seen under ideal conditions positively labels a large whale as a sperm whale.
 

Note

Only spelling mistakes, if any, in the above passage have been corrected. No other corrections, including grammatical, have been made so that the originality of the passage is maintained.