ACT Reading Dec. 2016 74H - Passage IV

Questions 31-40 are based on the following passage.

NATURAL SCIENCE: This passage is adapted from the article "Call of the Leviathan" by Eric Wagner (©2011 by Smithsonian Institution).

In 1839, in the first scientific treatise on the sperm

whale, Thomas Beale, a surgeon aboard a whaler, wrote

that it was "one of the most noiseless of marine ani­

mals." While they do not sing elaborate songs, like
5 humpbacks or belugas, in fact they are not silent.

Whalers in the 1800s spoke of hearing loud knocking,

almost like hammering on a ship's hull, whenever

sperm whales were present. Only in 1957 did two scien­

tists from the Woods Hole Oceanographic Institution
10 confirm the sailors' observations. Aboard a research

vessel, the Atlantis, they approached five sperm whales,

shut off the ship's motors and listened with an under­

water receiver. At first, they assumed the "muffled,

smashing noise" they heard came from somewhere on
15 the ship. Then they determined the sounds were coming

from the whales.

Biologists now believe that the sperm whale's

massive head functions like a powerful telegraph

machine, emitting pulses of sound in distinct patterns.
20 At the front of the head are the spermaceti organ, a

cavity that contains the bulk of the whale's spennaceti,

and a mass of oil-saturated fatty tissue. Two long nasal

passages branch away from the bony nares of the skull,

twining around the spermaceti organ and the fatty
25 tissue. The left nasal passage runs directly to the blow­

hole at the top of the whale's head. But the other twists

and turns, flattens and broadens, forming a number of

air-filled sacs capable of reflecting sound. Near the

front of the head sit a pair of clappers called "monkey
30 lips.

Sound generation is a complex process. To make

its clicking sounds, a whale forces air through the right

nasal passage to the monkey lips, which clap shut. The

resulting click! bounces off one air-filled sac and trav-
35 els back through the spermaceti organ to another sac

nestled against the skull. From there, the click is sent

forward, through the fatty tissue, and amplified out into

the watery world. Sperm whales may be able to manip­

ulate the shape of both the spermaceti organ and the
40 fatty tissue, possibly allowing them to aim their clicks.

Biologist Dr. Hal Whitehead has identified four

patterns of clicks. The most common clicks are used for

long-range sonar. So-called "creaks" sound like a

squeaky door and are used at close range when prey
45 capture is imminent. "Slow clicks" are made only by

large males, but no one knows precisely what they

signify. ("Probably something to do with mating,"

Whitehead guesses.) Finally, "codas" are distinct pat­

terns of clicks most often heard when whales are
50 socializing.

Codas are of particular interest. Whitehead has

found that different groups of sperm whales, called

vocal clans, consistently use different sets; the reper

toire of codas the clan uses is its dialect. Vocal clans
55 can be huge-thousands of individuals spread out over

thousands of miles of ocean. Clan members are not nec­

essarily related. Rather, many smaller, durable matrilin­-

eal units make up clans, and different clans have their

own specific ways of behaving.

60 A recent study in Animal Behaviour took the spe-

cialization of codas a step further. Not only do clans

use different codas, the authors argued, but the codas

differ slightly among individuals. They could be, in

effect, unique identifiers: names.

65 Whitehead cautions that a full understanding of

codas is still a long way off. Even so, he believes the

differences represent cultural valiants among the clans.

"Think of culture as information that is transmitted

socially between groups," he says. "You can make pre
70 dictions about where it will arise: in complex societies,

richly modulated, among individuals that form self­-

contained communities." That sounds to him a lot like

sperm whale society.

But most of a sperm whale's clicking, if not most
75 of its life, is devoted to one thing: finding food. And in

the Sea of Cortez, the focus of its attention is Dosidicus

gigas, the jumbo squid.

The most celebrated natural antagonism between

sperm whales and squid almost certainly involves the
80 jumbo squid's larger cousin, the giant squid, a species

that grows to 65 feet long. The relationship between

sperm whales and squid is pretty dramatic. A single

sperm whale can eat more than one ton of squid per

day. They do eat giant squid on occasion, but most of
85 what whales pursue is relatively small and over­-

matched. With their clicks, sperm whales can detect a

squid less than a foot long more than a mile away, and

schools of squid from even farther away. But the way

that sperm whales find squid was until recently a
90 puzzle.

Question 31 The main purpose of the passage is to