Post by Grey on Jun 21, 2013 22:11:56 GMT 5
Here's a thread to post any material you have that relates to the relationship between the various species of Dolphins & Sharks.
Hopefully this will be interesting, and also useful for matchups in the Interspecific Section.
Source 1 'elasmo-research.org'
Q: Do dolphins really beat up sharks?
- John
St. Louis, MO
A: Usually not, unless the shark is relatively small.
This notion is based on a much-publicized incident that took place at the Miami Seaquarium in the 1950's. When a Sandbar Shark showed a bit too much interest in the birth of a Bottlenose Dolphin calf, three of the adult male dolphins ganged up on the shark, butting it in the gills and stomach until it died. This 'protective' behavior was cemented in the public's mind by the television series, Flipper, produced in association with the Miami Seaquarium. There is a record of a Bottlenose Dolphin off California killing a two-foot Leopard Shark (Triakis semifasciata), then supporting it at the surface (which raises doubts about tales of dolphins 'rescuing' human swimmers: perhaps balancing an object on the rostrum is merely a dolphin game, devoid of any altruistic motivation).
During the 1960's, the U.S. Navy trained Bottlenose Dolphins to incapacitate large sharks by butting their delicate gill pouches. The dolphins quickly learned to attack Sandbar (Carcharhinus plumbeus), Lemon (Negaprion brevirostris), and Nurse Sharks (Ginglymostoma cirratum), but refused to approach a Bull Shark (Carcharhinus leucas) of similar size and shape. Sandbar, Lemon, and Nurse Sharks are not known to attack dolphins in the wild, but Bull Sharks are. This suggests that dolphins are able to classify sharks as either dangerous or not dangerous — an eminently practical taxonomy.
In the wild, similar-sized dolphins and sharks pretty much leave each other alone. Some 75% of wild dolphins show some degree of shark scarring — and we usually see only the ones that got away. I have pulled dolphin remains from the stomachs of many sharks over the years, particularly from Tiger Sharks (Galeocerdo cuvier). Thus, it seems that in most battles between dolphins and sharks in the wild, dolphins get the worst of the encounter.
www.elasmo-research.org/education/topics/b_corner.htm
Seems they are suggesting the aggressive shark species hold dominance over dolphins.
Source 2 What are the natural predators of dolphins?
Large sharks and killer whales are the only natural predators of dolphins. Tiger sharks, bull sharks, and great white sharks are the main species that attack dolphins. Humans have also posed a major threat to dolphins in recent years(in Japan the dolphin population was almost completely dessimated during the 1980's and 1990's).Predation risk may have been an important factor that led to the evolution of group living in dolphins. Furthermore, risk of shark predation appears to influence both habitat use and group sizes of dolphins in a variety of locations. In Sarasota Florida 31% of bottlenose dolphins bear bite scars while 36.6% of bottlenose dolphins in Moreton Bay Australia bear bite scars. These are very significant numbers, and could have easily spawned a group defense system among dolphin populations. Interestingly enough, Heithaus and Lawrence found that coastal dolphins exhibited more bite scars than pelagic dolphins. This seems to contradict theories that coastal dolphins remain safer from predators because of the shallow water. Also, few age and sex differences were noted in scarring rates. This implies that all dolphins are equally vulnerable to attack. Some scientists believe that shark attacks on dolphins are simply acts of aggressive behavior because dolphins and sharks utilize the same food sources. This has not been proven however, and more conclusive research needs to be carried out (Heithaus and Dill, 2002).
www.bio.davidson.edu/people/vecas....20predators.htm
Seems to back up the main points of the first source, but also highlights that shark attacks on dolphins is not rare.
More on the frwequency in this source -
Source 3 Natural Predators
Besides habitat destruction, pollution, and over-fishing, bottlenose dolphins are threatened by a few natural predators, most notably sharks. Recent studies show that several species of sharks, including the great white, tiger, and mako, attack and prey on bottlenose dolphins. In Western Australia, where extensive studies of dolphin-shark interactions have been conducted, as many as 70 percent of dolphins bear shark-attack scars, and an estimated 15 percent of the population may be attacked each year. The exact mortality rate from shark attack is unknown. The risk of shark predation may have been an important factor leading to the evolution of group living (for protection) in bottlenose dolphins.
More than 30 percent of Sarasota BayÂ’s bottlenose dolphins have visible shark attack scars, and seasonal population movements correlate with the abundance of sharks: Dolphins tend to move out of areas where sharks are abundant. In the presence of a shark, dolphin anti-predator behavior varies with the circumstances. Some simply swim away from the shark, others ram or bite it, and yet others launch coordinated group attacks to drive the predators away.
nationalzoo.si.edu/ConservationAn....eproduction.cfm
Source 4 Q: Is it true that where there are dolphins there are no sharks?
A. No, this is a fallacy. Although dolphins and sharks do not seek each
other to attack, they appear to have a mutual respect. Normally, a shark
will only attack a lone dolphin, a sick dolphin or a calf that strays from
its mother. In Port Phillip Bay, the large male dolphins that usually live
outside the bay come inside at the beginning of October, which is the same
time that the bronze whaler sharks come into the bay to mate and give
birth. Male dolphins form a guard around the females and young to protect
them during this time. Sharks usually keep their distance from the
dolphins.
Bronze whaler sharks are small, but aggressive. An adult Great White Shark
is about 5-7 times bigger, longer and scarier than a bronze whaler. In
fact, a small dolphin would fit between its jaws without touching the
teeth! However, Great Whites like eating seals, which are much easier to
detect, catch and according to new science, they prefer the taste (even
over humans!). I doubt there would ever be a scenario when an adult Great
White attacked a healthy pod of adult dolphins. Sharks are very wary
animals and unlikely to approach a pod that is guarding young.
www.madsci.org/posts/archives/2000-08/967564399.Zo.r.html
This source indicates again that smaller but aggressive shark species like the Bronze Whaler can be repelled by large male dolphins in a 'group defence'.
Source 5 - Evidence of predation by a tiger shark (Galeocerdo cuvier) on a spotted dolphin (Stenella attenuata) of O*ahu, Hawai*i
Witness accounts of shark predation on cetaceans
are rare.
Heithaus (2001b) recently reviewed predator-prey
and competitive interactions between sharks and
dolphins. Much of the evidence of shark/cetacean
interaction relies on stomach content studies (Bell &
Nichols, 1921; CliV & Dudley, 1991; Simpfendorfer
et al., 2001), on observations of scarring patterns
and wounds on live dolphins (Corkeron et al., 1987;
Cockcroft et al., 1989; Cockcroft, 1991; Bearzi
et al., 1997; Urian et al., 1998; Heithaus, 2001a) or
on carcasses beached or floating at sea, which often
bear signs of shark predation. However, in some
cases, these animals could have died of other causes
and may have been scavenged after death (Carey
et al., 1982; Long & Jones, 1996; Heithaus, 2001b).
The strategy used by the tiger shark during the
attack seems to confirm previous observations that
successful attacks on cetaceans occur more frequently
from the side/rear, while the higher incidence
of wounds and scars on the back/frontal
regions of the body of survivors indicates this is a
less eVective site of attack (Heithaus, 2001a). In the
case reported, the severing of the tailstock eVectively
ensured the immobilization of the victim,
which was left unable to escape. Interestingly,
another published report of a tiger shark attack on
a bottlenose dolphin (Tursiops truncatus) calf at
Monkey Mia, Australia showed a photograph of
the dead calf with a severed tail: witnesses to the
attack suspect the tail was severed before the shark
took a second fatal bite into the belly of the animal
(Mann & Barnett, 1999). Other observations
also support the hypothesis that many attacks on
odontocetes are directed to the tail (Arnold, 1972;
Cockcroft, 1991; Long & Jones, 1996).
If successful attacks are generally as quick and
flawless as the one witnessed in Hawaiian waters,
it is not surprising they are missed by potential
observers. To date, the rate of shark attacks on
cetaceans is unknown. Inferences on attack rates
can be made from unsuccessful attempts based on
wounds and scars (Cockcroft et al., 1989; Heithaus,
2001a). Nonetheless, lack of scars in a cetacean
population is not necessarily an indication of a low
rate of predation, but a possible indication of a
higher success rate of the predator, since wounded
dolphins only represent misses.
Irvine et al. (1973) reported that between 20 and
50% of bottlenose dolphins living along the shallow
waters of Florida and Texas bear scars inflicted by
sharks.
Sharks, on the other hand, rely on chemical,
electrical and visual cues to find their prey. Their
success in killing a dolphin may depend on opportunity
and speed. Norris et al. (1994) present a
report by Springer, which illustrates a possible
cooperative eVort by sharks to kill a common
dolphin (Delphinus delphis) by surrounding a school
for several hours and flanking the dolphins until an
opportunity is provided. It is common in the open
ocean to find multi-species aggregation where
sharks and dolphins all follow large schooling fish
(Au, 1991). The continued presence of sharks
around dolphin schools may provide many opportunities
for predation although cetaceans do not
appear to be the main staple of any shark species
(Heithaus, 2001b)."
www.alaskasealife.org/New/Contribute/pdf/Maldini_2003.pdf
Well this source indicates, even though it was only a juvenile dolphin and the shark must have been quite larger, that their attacks can quick and efficient.
The good news is for dolphins, as evidenced by the number of living dolphins with shark attack scars, is the heal quickly and not al attacks are fatal.
Source 6 - Report on the healing of a large woundin a Bottlenose Dolphin Tursiops truncatus
THERE are several reports that dolphins (Delphinidae) sustain injuries from shark bites (Corkeron et al. 1987a) and that these wounds heal rapidly (Corkeron et al. 1987b; Bruce-Allen and Geraci 1985).
On 20 May 1993 a mature male Bottlenose Dolphin, “Freddy”, arrived at the feeding witha large open wound located on his left side,above and approximately level with the flipper(see Fig. 1). This injury must have occurred during the previous 24 hours since the dolphin had attended the feeding session on 19 May1993 and did not have the wound then. The lesion was roughly semi-circular in shape and approximately 45 cm in diameter. It penetrated approximately 3 cm into the dolphin’s blubber layer at the deepest point, and in two placesmuscle tissue was visible. The wound wasdeepest on the dorsal side, and several punctures resembling teeth marks were presenton its ventral aspect. The shape and type of injury was consistent with a shark bite. Previous research indicates that over a third of all dolphins in Moreton Bay have evidence of sharkbites (Corkeron et al. 1987b)."
www.dolphinisland.com.au/dolphinweb/research/papers/paper4.pdf
The dolphin, lived indicating their hardiness and why so many living dolphins bear scars.
Comments?
--------------------------------------------------------------------------------
Shark v Dolphin Comparison from Oregon Coast Aquarium
Evolution
Modern dolphins have been around for 12-15 million years and whales for over 50 million. Sharks have been prowling the world's oceans over 400 million years, making dolphins a bunch of flipper-come-latelys.
Advantage: Sharks
Habitats
Dolphins live in open water, near- and offshore, in cool polar waters and warm tropical seas, even in freshwater rivers. Sharks can be found in all these habitats and in the deep sea to at least 10,000 feet.
Advantage: Even
Skeleton
Dolphin skeletons are made of run-of-the-mill, stiff, heavy, boring old bone. Shark skeletons are made of flexible and fascinating cartilage. Shark skeletons are lighter, more flexible, strong where they need to be and heal very quickly.
Advantage: Sharks
Breathing in the Ocean
A dolphin's nostrils are located on the top of its head. This "blowhole" makes it very easy to get a breath at the surface. But what a pain! Go the surface every time you need to breathe?! Sharks just breathe the water.
Advantage: Sharks
Teeth
Most dolphins have conical, daggerlike teeth for grasping prey. The Franscicana dolphin may have up to 240 teeth. A single shark, however, may have several thousand. Shark teeth vary in shape according to what they eat.
Advantage: Sharks
Senses
Dolphins are big on sound and have good eyesight but absolutely no sense of smell. Sharks are all about smell. But their noses are just one facet of possibly the most impressive array of senses in the entire animal kingdom.
Advantage: Sharks
Reputation
Smiling, benevolent, human-friendly media darlings versus scowling, mindless, man-eating monsters and villains. The truth? Neither is accurate. Still, the advantage is clear
Advantage: Dolphins
Diversity
There are around 32 species of dolphins and porpoises. There are over 450 species of sharks, maybe as many as 480. Shark species come in an amazing array of shapes and sizes, from less than a foot to almost 50 feet.
Advantage: Sharks
Body Form
Dolphins have a sleek, streamlined shape with stiff fins for steering and a strong tail for propulsion. Perfect for life in the ocean. Too bad sharks had it figured out 385 million years earlier.
Advantage: Sharks
Skin
Dolphin skin is smooth, rubbery and good for biting. Shark skin is tough, elastic and covered with tiny teeth. It provides excellent protection from predators and aids in swimming by channeling water along the shark's body.
Advantage: Sharks
Reproduction
Dolphin embryos are nourished by the mother within her womb and then born live. Very advanced. Guess what? Sharks do it, too. Some species bear their young live and for a little variety, some others lay eggs.
Advantage: Sharks
Feeding styles
Dolphins use sound to locate their prey and may work together to capture it. Sharks will use teeth, tails, gill rakers, sound, smell, sight, lips, head and even electricity to find, catch and devour their food.
Advantage: Sharks
Intelligence
Dolphins are highly intelligent and highly trainable. Some have even been trained to retrieve unexploded mines by the Navy. You could never get a shark to retrieve anything referred to as "unexploded," so who's really smarter?
Advantage: Dolphins
Conservation Status
Dolphins may be protected in the U.S., but they're still hunted in other parts of the world. Several dolphin populations are dangerously low. Sharks are facing worldwide declines fueled by commercial fishing, bycatch and habitat loss.
Advantage: Dolphins
Seems the shark has many clear advantages over the dolphin.
Hopefully this will be interesting, and also useful for matchups in the Interspecific Section.
Source 1 'elasmo-research.org'
Q: Do dolphins really beat up sharks?
- John
St. Louis, MO
A: Usually not, unless the shark is relatively small.
This notion is based on a much-publicized incident that took place at the Miami Seaquarium in the 1950's. When a Sandbar Shark showed a bit too much interest in the birth of a Bottlenose Dolphin calf, three of the adult male dolphins ganged up on the shark, butting it in the gills and stomach until it died. This 'protective' behavior was cemented in the public's mind by the television series, Flipper, produced in association with the Miami Seaquarium. There is a record of a Bottlenose Dolphin off California killing a two-foot Leopard Shark (Triakis semifasciata), then supporting it at the surface (which raises doubts about tales of dolphins 'rescuing' human swimmers: perhaps balancing an object on the rostrum is merely a dolphin game, devoid of any altruistic motivation).
During the 1960's, the U.S. Navy trained Bottlenose Dolphins to incapacitate large sharks by butting their delicate gill pouches. The dolphins quickly learned to attack Sandbar (Carcharhinus plumbeus), Lemon (Negaprion brevirostris), and Nurse Sharks (Ginglymostoma cirratum), but refused to approach a Bull Shark (Carcharhinus leucas) of similar size and shape. Sandbar, Lemon, and Nurse Sharks are not known to attack dolphins in the wild, but Bull Sharks are. This suggests that dolphins are able to classify sharks as either dangerous or not dangerous — an eminently practical taxonomy.
In the wild, similar-sized dolphins and sharks pretty much leave each other alone. Some 75% of wild dolphins show some degree of shark scarring — and we usually see only the ones that got away. I have pulled dolphin remains from the stomachs of many sharks over the years, particularly from Tiger Sharks (Galeocerdo cuvier). Thus, it seems that in most battles between dolphins and sharks in the wild, dolphins get the worst of the encounter.
www.elasmo-research.org/education/topics/b_corner.htm
Seems they are suggesting the aggressive shark species hold dominance over dolphins.
Source 2 What are the natural predators of dolphins?
Large sharks and killer whales are the only natural predators of dolphins. Tiger sharks, bull sharks, and great white sharks are the main species that attack dolphins. Humans have also posed a major threat to dolphins in recent years(in Japan the dolphin population was almost completely dessimated during the 1980's and 1990's).Predation risk may have been an important factor that led to the evolution of group living in dolphins. Furthermore, risk of shark predation appears to influence both habitat use and group sizes of dolphins in a variety of locations. In Sarasota Florida 31% of bottlenose dolphins bear bite scars while 36.6% of bottlenose dolphins in Moreton Bay Australia bear bite scars. These are very significant numbers, and could have easily spawned a group defense system among dolphin populations. Interestingly enough, Heithaus and Lawrence found that coastal dolphins exhibited more bite scars than pelagic dolphins. This seems to contradict theories that coastal dolphins remain safer from predators because of the shallow water. Also, few age and sex differences were noted in scarring rates. This implies that all dolphins are equally vulnerable to attack. Some scientists believe that shark attacks on dolphins are simply acts of aggressive behavior because dolphins and sharks utilize the same food sources. This has not been proven however, and more conclusive research needs to be carried out (Heithaus and Dill, 2002).
www.bio.davidson.edu/people/vecas....20predators.htm
Seems to back up the main points of the first source, but also highlights that shark attacks on dolphins is not rare.
More on the frwequency in this source -
Source 3 Natural Predators
Besides habitat destruction, pollution, and over-fishing, bottlenose dolphins are threatened by a few natural predators, most notably sharks. Recent studies show that several species of sharks, including the great white, tiger, and mako, attack and prey on bottlenose dolphins. In Western Australia, where extensive studies of dolphin-shark interactions have been conducted, as many as 70 percent of dolphins bear shark-attack scars, and an estimated 15 percent of the population may be attacked each year. The exact mortality rate from shark attack is unknown. The risk of shark predation may have been an important factor leading to the evolution of group living (for protection) in bottlenose dolphins.
More than 30 percent of Sarasota BayÂ’s bottlenose dolphins have visible shark attack scars, and seasonal population movements correlate with the abundance of sharks: Dolphins tend to move out of areas where sharks are abundant. In the presence of a shark, dolphin anti-predator behavior varies with the circumstances. Some simply swim away from the shark, others ram or bite it, and yet others launch coordinated group attacks to drive the predators away.
nationalzoo.si.edu/ConservationAn....eproduction.cfm
Source 4 Q: Is it true that where there are dolphins there are no sharks?
A. No, this is a fallacy. Although dolphins and sharks do not seek each
other to attack, they appear to have a mutual respect. Normally, a shark
will only attack a lone dolphin, a sick dolphin or a calf that strays from
its mother. In Port Phillip Bay, the large male dolphins that usually live
outside the bay come inside at the beginning of October, which is the same
time that the bronze whaler sharks come into the bay to mate and give
birth. Male dolphins form a guard around the females and young to protect
them during this time. Sharks usually keep their distance from the
dolphins.
Bronze whaler sharks are small, but aggressive. An adult Great White Shark
is about 5-7 times bigger, longer and scarier than a bronze whaler. In
fact, a small dolphin would fit between its jaws without touching the
teeth! However, Great Whites like eating seals, which are much easier to
detect, catch and according to new science, they prefer the taste (even
over humans!). I doubt there would ever be a scenario when an adult Great
White attacked a healthy pod of adult dolphins. Sharks are very wary
animals and unlikely to approach a pod that is guarding young.
www.madsci.org/posts/archives/2000-08/967564399.Zo.r.html
This source indicates again that smaller but aggressive shark species like the Bronze Whaler can be repelled by large male dolphins in a 'group defence'.
Source 5 - Evidence of predation by a tiger shark (Galeocerdo cuvier) on a spotted dolphin (Stenella attenuata) of O*ahu, Hawai*i
Witness accounts of shark predation on cetaceans
are rare.
Heithaus (2001b) recently reviewed predator-prey
and competitive interactions between sharks and
dolphins. Much of the evidence of shark/cetacean
interaction relies on stomach content studies (Bell &
Nichols, 1921; CliV & Dudley, 1991; Simpfendorfer
et al., 2001), on observations of scarring patterns
and wounds on live dolphins (Corkeron et al., 1987;
Cockcroft et al., 1989; Cockcroft, 1991; Bearzi
et al., 1997; Urian et al., 1998; Heithaus, 2001a) or
on carcasses beached or floating at sea, which often
bear signs of shark predation. However, in some
cases, these animals could have died of other causes
and may have been scavenged after death (Carey
et al., 1982; Long & Jones, 1996; Heithaus, 2001b).
The strategy used by the tiger shark during the
attack seems to confirm previous observations that
successful attacks on cetaceans occur more frequently
from the side/rear, while the higher incidence
of wounds and scars on the back/frontal
regions of the body of survivors indicates this is a
less eVective site of attack (Heithaus, 2001a). In the
case reported, the severing of the tailstock eVectively
ensured the immobilization of the victim,
which was left unable to escape. Interestingly,
another published report of a tiger shark attack on
a bottlenose dolphin (Tursiops truncatus) calf at
Monkey Mia, Australia showed a photograph of
the dead calf with a severed tail: witnesses to the
attack suspect the tail was severed before the shark
took a second fatal bite into the belly of the animal
(Mann & Barnett, 1999). Other observations
also support the hypothesis that many attacks on
odontocetes are directed to the tail (Arnold, 1972;
Cockcroft, 1991; Long & Jones, 1996).
If successful attacks are generally as quick and
flawless as the one witnessed in Hawaiian waters,
it is not surprising they are missed by potential
observers. To date, the rate of shark attacks on
cetaceans is unknown. Inferences on attack rates
can be made from unsuccessful attempts based on
wounds and scars (Cockcroft et al., 1989; Heithaus,
2001a). Nonetheless, lack of scars in a cetacean
population is not necessarily an indication of a low
rate of predation, but a possible indication of a
higher success rate of the predator, since wounded
dolphins only represent misses.
Irvine et al. (1973) reported that between 20 and
50% of bottlenose dolphins living along the shallow
waters of Florida and Texas bear scars inflicted by
sharks.
Sharks, on the other hand, rely on chemical,
electrical and visual cues to find their prey. Their
success in killing a dolphin may depend on opportunity
and speed. Norris et al. (1994) present a
report by Springer, which illustrates a possible
cooperative eVort by sharks to kill a common
dolphin (Delphinus delphis) by surrounding a school
for several hours and flanking the dolphins until an
opportunity is provided. It is common in the open
ocean to find multi-species aggregation where
sharks and dolphins all follow large schooling fish
(Au, 1991). The continued presence of sharks
around dolphin schools may provide many opportunities
for predation although cetaceans do not
appear to be the main staple of any shark species
(Heithaus, 2001b)."
www.alaskasealife.org/New/Contribute/pdf/Maldini_2003.pdf
Well this source indicates, even though it was only a juvenile dolphin and the shark must have been quite larger, that their attacks can quick and efficient.
The good news is for dolphins, as evidenced by the number of living dolphins with shark attack scars, is the heal quickly and not al attacks are fatal.
Source 6 - Report on the healing of a large woundin a Bottlenose Dolphin Tursiops truncatus
THERE are several reports that dolphins (Delphinidae) sustain injuries from shark bites (Corkeron et al. 1987a) and that these wounds heal rapidly (Corkeron et al. 1987b; Bruce-Allen and Geraci 1985).
On 20 May 1993 a mature male Bottlenose Dolphin, “Freddy”, arrived at the feeding witha large open wound located on his left side,above and approximately level with the flipper(see Fig. 1). This injury must have occurred during the previous 24 hours since the dolphin had attended the feeding session on 19 May1993 and did not have the wound then. The lesion was roughly semi-circular in shape and approximately 45 cm in diameter. It penetrated approximately 3 cm into the dolphin’s blubber layer at the deepest point, and in two placesmuscle tissue was visible. The wound wasdeepest on the dorsal side, and several punctures resembling teeth marks were presenton its ventral aspect. The shape and type of injury was consistent with a shark bite. Previous research indicates that over a third of all dolphins in Moreton Bay have evidence of sharkbites (Corkeron et al. 1987b)."
www.dolphinisland.com.au/dolphinweb/research/papers/paper4.pdf
The dolphin, lived indicating their hardiness and why so many living dolphins bear scars.
Comments?
--------------------------------------------------------------------------------
Shark v Dolphin Comparison from Oregon Coast Aquarium
Evolution
Modern dolphins have been around for 12-15 million years and whales for over 50 million. Sharks have been prowling the world's oceans over 400 million years, making dolphins a bunch of flipper-come-latelys.
Advantage: Sharks
Habitats
Dolphins live in open water, near- and offshore, in cool polar waters and warm tropical seas, even in freshwater rivers. Sharks can be found in all these habitats and in the deep sea to at least 10,000 feet.
Advantage: Even
Skeleton
Dolphin skeletons are made of run-of-the-mill, stiff, heavy, boring old bone. Shark skeletons are made of flexible and fascinating cartilage. Shark skeletons are lighter, more flexible, strong where they need to be and heal very quickly.
Advantage: Sharks
Breathing in the Ocean
A dolphin's nostrils are located on the top of its head. This "blowhole" makes it very easy to get a breath at the surface. But what a pain! Go the surface every time you need to breathe?! Sharks just breathe the water.
Advantage: Sharks
Teeth
Most dolphins have conical, daggerlike teeth for grasping prey. The Franscicana dolphin may have up to 240 teeth. A single shark, however, may have several thousand. Shark teeth vary in shape according to what they eat.
Advantage: Sharks
Senses
Dolphins are big on sound and have good eyesight but absolutely no sense of smell. Sharks are all about smell. But their noses are just one facet of possibly the most impressive array of senses in the entire animal kingdom.
Advantage: Sharks
Reputation
Smiling, benevolent, human-friendly media darlings versus scowling, mindless, man-eating monsters and villains. The truth? Neither is accurate. Still, the advantage is clear
Advantage: Dolphins
Diversity
There are around 32 species of dolphins and porpoises. There are over 450 species of sharks, maybe as many as 480. Shark species come in an amazing array of shapes and sizes, from less than a foot to almost 50 feet.
Advantage: Sharks
Body Form
Dolphins have a sleek, streamlined shape with stiff fins for steering and a strong tail for propulsion. Perfect for life in the ocean. Too bad sharks had it figured out 385 million years earlier.
Advantage: Sharks
Skin
Dolphin skin is smooth, rubbery and good for biting. Shark skin is tough, elastic and covered with tiny teeth. It provides excellent protection from predators and aids in swimming by channeling water along the shark's body.
Advantage: Sharks
Reproduction
Dolphin embryos are nourished by the mother within her womb and then born live. Very advanced. Guess what? Sharks do it, too. Some species bear their young live and for a little variety, some others lay eggs.
Advantage: Sharks
Feeding styles
Dolphins use sound to locate their prey and may work together to capture it. Sharks will use teeth, tails, gill rakers, sound, smell, sight, lips, head and even electricity to find, catch and devour their food.
Advantage: Sharks
Intelligence
Dolphins are highly intelligent and highly trainable. Some have even been trained to retrieve unexploded mines by the Navy. You could never get a shark to retrieve anything referred to as "unexploded," so who's really smarter?
Advantage: Dolphins
Conservation Status
Dolphins may be protected in the U.S., but they're still hunted in other parts of the world. Several dolphin populations are dangerously low. Sharks are facing worldwide declines fueled by commercial fishing, bycatch and habitat loss.
Advantage: Dolphins
Seems the shark has many clear advantages over the dolphin.
Bone is definitely vastly underrated compared to cartilage, I think that’s because cartilaginous skeletons are somehow more "exotic" to the modern observer or something like that.
