Great White Shark Carcharodon carcharias Sociable Behaviour
by
Rachael Griffin
2001
Abstract
The purpose of this paper is to evaluate social behaviour in Carcharodon carcharias, white
shark, by examining their evolved predatory abilities. Carcharodon carcharias have adapted to
life history of pinnipeds (seals) which molt at coastal locations. Adaptations of Carcharodon
carcharias include electroreception , acute vision, and a countercurrent heat exchange system.
These adaptations have increased the brain size of white sharks. A larger brain increases
their ability to learn sociable behaviours. A review of literature on Carcharodon carcharias
biology and behaviour supports the view that white sharks display social behaviour. Schooling
juveniles are captured in a large numbers at once. Born to a pack of several individuals of
the same age class promotes social bonding. Carcharodon carcharias often move in and out
of range simultaneously. Coordinated movements identify patrolling within a group. White
sharks are solitary hunters that frequent the same conspecifics, individuals of the same species.
Two individual white sharks frequent each other more than the other Carcharodon carcharias
of a patrolling group. Sociable behaviour occurs instead of seriously injuring each other and
decreasing chances at acquiring more food energy. White sharks search for prey independently
but remain close enough to sense and exploit each other's kills.
Keywords
Ampulli of Lorenzeni, Carcharodon carcharias, countercurrent heat exchange, social behaviour,
vision, white shark,
Introduction
The fossil record of Carcharodon begins in the Paleocene period about 60 million years ago.
The total length (TL) of an adult Carcharodon carcharias is between 6 to 14 meters, females
are larger than males (McConnaughey and McConnaughey 1985). The white shark was a big
game fish, but now is protected in certain areas as over-fishing has reduced its numbers. White
sharks are found worldwide in tropical and temperate seas, more commonly in the latter (Potts
and Sawby 1997). They hunt , < 37 m from the surface , 1.3 km from the shore (Klimley et al.
2001b). Around North and South America, Carcharodon carcharias are found from Alaska to
Gulf of California, and from Southern Newfoundland to Brazil including the Gulf of Mexico
(McConnaughey and McConnaughey 1985). Carcharodon carcharias scavenges and preys on
bony fish, sharks, sea turtles, pinnipeds, and cetaceans (whales, dolphins, and porpoises) and
have even been known to attack boats off northwestern Vancouver Island (Klimley and Ainley
1996). Carcharodon carcharias are mainly a coastal species found between the surface and
depths of 1280 meters (Potts and Swaby 1997). Carcharodon carcharias bear between 9 and 14
live young (Francis 1996). Parturition, birth to live young, occurs in temperate waters, during
the spring and summer months.
Carcharodon carcharias can detect weak electrical cues from muscle contractions of their prey.
Small pores on the white shark’s head, snout, and mouth lead to conductive jelly-filled canals
that terminate in receptor cells, called Ampullae of Lorenzini. The received electroreception
information is transmitted directly to the central nervous system. The need to integrate sensory
information has increased the size of the Carcharodon carcharias cerebellum (Kardong 1998).
Carcharodon carcharias have good vision and hearing capabilities. Surrounding the orbits of
the eye, near the brain, are orbital retes (dense network of capillaries) enhancing vision ability
(Helfman 1997). A white shark's retina is dominated with rods, which are active at night and
twilight. They allow light to strike the cells twice increasing the likelihood of detection of
prey by Carcharodon carcharias. Less cones, in the retina, increase daytime ability and is
associated with colour vision (Helfman 1997). Carcharodon carcharias vision is more similar
to mammals than most other fishes (Helfman 1997). Separation distance between two individual
Carcharodon carcharias is less than random (Klimley et al. 2001a). Two white sharks swim
within visual range that is less than water visibility (Klimley et al. 2001a).. White sharks can
also detect prey with macule, nerve cells linked to granules that vibrate in response to sound.
These predatory adaptations correlate with increase in brain mass (Kardong 1998).
The blood transport of Carcharodon carcharias transports heat produced as a by-product
of their exercising muscles. Blood circulation to extremities is warm but seawater is cold.
Therefore, much heat would be lost to the environment were it not for specialized features of the
circulatory system. White sharks are endothermic, a warmer body temperature relative to their
environment, because of a countercurrent heat exchange system. Carcharodon carcharias have
heat exchangers in the circulatory system. Masses of parallel arteries and veins form the heat
exchangers, the rete mirabilia (Goldman et al. 1996). This is an elaborate intertwining network
between outgoing arteries and returning veins. Blood in a rete establishes a countercurrent
pattern between outgoing arteries and these returning veins. Before the blood reaches the
integument (skin) warmth is passed through the rete. Heat carried in the arteries is transferred
almost completely to the returning blood in the veins. By the time blood reached the extremities,
little heat remains to be dissipated to the environment. Therefore, retes function as heat
blockers to prevent body heat from being lost through the extremities. White sharks also have
a thick ventricle similar to the left ventricle in humans to pump blood efficiently throughout
the body (Goldman 1997). Retes have enabled Carcharodon carcharias to develop a optimal
physiological operating temperature. Other benefits of warm blood include increased rates of
neural, digestive, and muscular activity (Goldman 1997). Increased digestion enables increased
absorbency of energy from food. Carcharodon carcharias have elevated brain temperatures
enabling heightened cognition to capture swift agile prey (Goldman 1997). Carcharodon
carcharias have evolved physiological mechanisms to efficiently prey on warm bodied aquatic
animals by thermoregulation. Warm blood keeps the brain warm. Therefore, enhancing quick
response time from integrated sensory information.
White sharks have larger brains than ectothermic vertebrates (Demski and Northcutt 1996). The
brain-body mass ratios of Carcharodon carcharias overlap, in relative size and complexity,
to brains of mammals (Demski and Northcutt 1996). The cerebrum, forebrain, is the largest
part of the vertebrate brain. It consists of two cerebral cortex hemispheres with Grey matter
surrounding each hemisphere. Grey matter contains billions of nerve cells to integrate sensory
and neural functions. The cerebrum enlarges during vertebrate evolution (Kardong 1998).
An increase in the size of the cerebrum is due to increasingly complex behaviours and muscle
control. Reception of olfactory, visual, and other sense information is a major function of the
cerebrum (Kardong 1998). The cerebrum processes data and returns information back to the
central nervous system. Enlargement of the forebrain reflects its increasing role within the
locomotion system. A larger cerebrum offers abilities in learning and thinking (Myers 1995),
enabling Carcharodon carcharias to become even more adaptive to its predatory niche. The
cerebellum, hindbrain, is smaller than the cerebrum but also consists of two hemispheres with
a core of white matter and outer Grey matter. The cerebellum’s function is to learn using short
and long-term memory, and to coordinate muscles for balance (Kardong 1998). Active aquatic
organisms navigate in three dimensions so equilibrium and balance are very important. Thus,
the cerebellum is well developed. The cerebellum helps to control ambushes by Carcharodon
carcharias on seals from below the water’s surface (Demski and Northcutt 1996). Brain
development increases behavioural capabilities in white sharks (Demski and Northcutt 1996).
Increased brain mass permits Carcharodon carcharias to display behaviours such as tail
slaps (TS), breaching (BR), and repeated arial gaping (RAG). Sociability in the white sharks
is causing these behaviours. An evaluation of behaviour will determine why Carcharodon
carcharias socialize. I hypothesize that Carcharodon carcharias are social because this
decreases their predatory energy requirements. Staying around other white sharks promote their
chances at taking part in each other’s feedings. If this is true then Carcharodon carcharias will
spend more time with other sharks, than being alone, and will also display social behaviour to
other white sharks. This analysis will reveal how Carcharodon carcharias predatory adaptations
promote intraspecific and interspecific social behaviour.
Methods and Materials
An evaluation of relevant literature on Carcharodon carcharias evolved predatory adaptations
and its social behaviour. I first read ichthyology and great white shark texts from the Woodward
library. Then searched scientific databases for journal articles on the biology and hunting
beahviour of white sharks. Other materials used include web sites with photographs of
Carcharodon carcharias behaviour. Information from all these resources was analyzed to
identify why and how Carcharodon carcharias exhibit sociable behaviour.
Results
Stomach temperature is a good estimate of core body temperature. Fig. 1 shows how
Carcharodon carcharias can keep their body temperature warm in different temperatures of
water.
FIG. 1. Stomach temperatures versus water temperature at mean swimming depth for three (open circles,
squares (2), and closed circles) Carcharodon careharias (Goldman 1997).
Two individual Carcharodon carcharias frequent each other more than time spent alone or in
a group (Fig. 2). Five sharks patrolled the same area near a seal colony at Ano Nueno Islands,
California for two weeks (Klimley et al. 2001b). The area patrolled by three sharks overlapped
more than the two other sharks. Two of these three sharks spent most of their time with each
other. Predatory adaptations can facilitate social bonding. Electroreception, vision, and hearing
increase detection of conspecifics.
FIG. 2. Carcharodon carcharias (W1) time present (%) alone and with the four other sharks (W2 to W4)
(Klimley et al. 2001b).
Displays in Carcharodon carcharias such as TS and BR occur between two white sharks
(Klimley et al. 1996). Fig. 3 shows how a TS of a Carcharodon carcharias consists of it tilting ,
lifting, and beating its caudal fin out of the water.
FIG. 3. Motor components of tail slap. (A) After rotating onto its side,
the white shark is lifting its tail from the water; (B) the shark’s tail and
posterior torso are poised to slap the water (Klimley and Ainley 1996).
Fig. 4 displays how the TS presentation splashes water in the direction of another white shark.
FIG. 4. Depiction of tail slaps performed by (frame 2, 3, 5, and 6) the Intact Caudal (IC) and (frame
4 and 6) Cut Caudal (CC) white sharks during a passing movements in one day (Klimley and Ainley
1996).
The white sharks in Fig. 4 swam repeatedly by each other at the surface, approaching within 1m
of each other every time. As they passed, IC directed four splashes at CC, which splashed water
twice in the direction of IC. CC performed a third TS at IC slightly later (not shown in Fig. 4).
During these passes, IC was positioning itself between CC and a seal carcass. IC displays were
more vigorous than CC and resulted in it winning the combat and returning to bite its prey.
Fig. 5 shows Carcharodon carcharias BR. This behaviour consists of a white shark propelling
all or two thirds of their body out of the water at a 30-90 degree angle to the sea water surface
landing with a large splash. BR is witnessed during feeding battles (Klimley et al. 1996).
FIG. 5. Carcharodon carcharias breaches by throwing its body out of the water.
RAG can be displayed by Carcharodon carcharias to boat dwellers (Figs. 6 and 7). The
behaviour includes Carcharodon carcharias holding its head out of the water and opening and
closing its mouth in a series of slow, rhythmic partial gapes while awkwardly swimming slowly
along the surface. RAG can follow hindered feeding attempts when bait is withdrawn (Strong
JR. 1996). Contact with air is required to initiate RAG, as it is not witnessed underwater.
FIG. 6. Carcharodon carcharias displaying its palate towards a boat occupant.
Fig. 7 shows how a brave person in a boat can actually touch the nose of Carcharodon
carcharias while it is RAG.
FIG. 7. A person touching the nose of Carcharodon carcharias while it is ariel gaping and showing
its palate.
Discussion
Adaptations in white sharks increase their ability to detect prey species. These adaptations
enable interaction among Carcharodon carcharias individuals. Adaptations such as
electrochemical reception, acute vision, and warm blood all increase brain mass. Retes
have evolved to maintain highest physiological efficiency by maintaining optimal operating
temperature in different water column temperatures. Endothermy allows Carcharodon
carcharias to pursue their fast moving prey in cold waters. Warm blood increases brain activity
(Kardong 1998). Selection pressures drive brain development. These adaptations facilitate
social behaviour. Adapting to hunt for food in murky cold water has increased the ability for
social behaviour in white sharks.
Young Carcharodon carcharias grows up together in a school and form social bonds to their
same age group (Francis 1996). Klimley et al. (2001a,b) found that individual Carcharodon
carcharias will spend most of their time with another familiar shark. Highly social, nonrandom,
swim modes such as rapid head on turns and staying within visual range of each other represent
Carcharodon carcharias working in unison with one another . It is disadvantageous for sharks
to bite each other and decrease each other’s chance for increased food abundance. Therefore, TS
and BR warn other sharks from exploiting each other's prey. The recipient shark perceives with
electoreception, vision, hearing, and cognition.
Carcharodon carcharias TS and BR more in a large group than when alone (Klimley et al.
2001b). Socializing increases feeding rate relative to foraging away from sharks (Klimley et al.
2001b). The benefits to allowing one shark eat your prey include a trade off between sharing a
carcass and gaining the chance to feast without having to expend energy to do the killing in the
future. White shark alliances could be made up of a dominant and subordinate members. By
not harming the other shark, the TS signaler gains an energy advantage by increasing its chances
at exploiting the other shark’s prey. TS occur on departure of Carcharodon carcharias kills to
another white shark (Klimley et al. 2001b). A shark fed further on a seal only if the vigor and
frequency of its TS are greater than those of its opponent (Klimley et al. 1996). Therefore, TS
is an agonistic display to ward off competitors. BR is used much less commonly but may be
a higher intensity agonistic display. These behaviours may also be used for courtship displays
(Barlow 1996).
Increased brain activity promotes displayed behaviours in Carcharodon carcharias. Strong Jr.
(1996) suggested five working theories to explain RAG. First, RAG may be associated with
ingestion and or respiration. As the head enters the water, after a lung, large amounts of air leave
the mouth and gills. Therefore, RAG can help eliminate air trapped in the buccal cavity and
or stomach. Second, the situation preventing the Carcharodon carcharias from completing a
predatory behaviour may promote RAG. Thirdly, RAG may decrease frustration. After RAG
some sharks bite ship parts. Similar biting of conspecifics has been observed in Carcharodon
carcharias aggregations near food sources. Larger conspecifics will stop a smaller Carcharodon
carcharias from feeding and induce aggression behaviour (Strong Jr. 1996). Fourth, RAG may
be to increase probability of seizing prey at the air-water interface. Finally, RAG may be to
intimidate and confuse prey. For example, killer whales create water disturbance at the water’s
surface to confuse pinnepeds into the water (Strong Jr. 1996). Thwarting and frustration are
anthropomorphic terms and should be avoided. Comparison of behaviour components with these
RAG theories reveals that predator-prey communication is the best possible hypothesis 9Strong
Jr. 1996).
Adapting to cold, low visibility, water enable white sharks to specialize an oceanic niche. For
Carcharodon carcharias to be social they would show certain behaviours to conspecifics.
Carcharodon carcharias do repeatedly respond to each other in similar scenarios. Complex
predatory adaptations increase brain mass and cognitive learning ability. Social bonds decrease
time spent to find prey. Learning to socialize creates a positive feedback to increase efficient
predation. Studies on RAG are required to identify the bazaar displays towards boaters. It
may be to ward off threats like a canine bearing its palate and teeth. More research is needed
from various Carcharodon carcharias populations to identify more significance in socializing
behaviours. Carcharodon carcharias may even have their own social culture.
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