History of Dolphin in Timeline
Dolphins are aquatic mammals belonging to the Odontoceti clade. They are distributed among several families, including Delphinidae, Platanistidae, Iniidae, Pontoporiidae, and the possibly extinct Lipotidae. Currently, there are approximately 40 recognized extant species of dolphins.
1933: Hybrid Dolphins Beached
In 1933, three hybrid dolphins, resulting from a Risso's dolphin and bottlenose dolphin mating, were found beached off the Irish coast. This event demonstrated the possibility of interspecies breeding within dolphins.
1962: Start of Queensland's Shark Culling Program
Since 1962, Queensland's shark culling program has killed roughly 50,000 sharks and also thousands of dolphins as bycatch, highlighting the negative impact of such programs on dolphin populations.
1976: Poole Coat of Arms Depiction
Since 1976, the dolphin on the coat of arms of the town of Poole, Dorset, England, has been depicted naturalistically, diverging from its previously stylized heraldic form.
1982: El Niño Warming Event
In 1982, the 1982-83 El Niño warming event caused marine animal migration in California.
1984: Pacific White-Sided Dolphin Increase in Canada
From 1984 to 1998, the Pacific white-sided dolphin had an increase in occurrence on the west coast of Canada, indicating a possible range shift due to changing environmental conditions.
1985: First Wholphin Born in Captivity
In 1985, the first wholphin, a hybrid of a false killer whale and a bottlenose dolphin, was born in captivity at Sea Life Park in Hawaii, marking a significant event in the study of dolphin hybridization.
1988: Billie's Rescue and Tail-Walking Observation
In 1988, a female dolphin named Billie was rescued after being trapped in a polluted marina. After recuperating with captive dolphins and observing their tail-walking, she began performing the trick herself after being released.
1991: Tilikum's First Incident
In 1991, Tilikum played a role in the death of three people in three different incidents.
1992: White-Beaked Dolphin Decreased in Scotland
From 1992 to 2003, white-beaked dolphins in northwest Scotland decreased while common dolphins (local to warmer waters) have increased, indicating a range shift possibly due to warming waters.
1992: Tilikum at SeaWorld
In 1992, Tilikum lived at SeaWorld until his death in 2017. Tilikum played a role in the death of three people in three different incidents.
1994: Fatal Dolphin Attack in Brazil
In 1994, off the coast of Brazil, a man died after being attacked by a bottlenose dolphin named Tião. Tião had suffered harassment by human visitors.
1995: Marten and Psarakos Dolphin Self-Awareness Test
In 1995, Marten and Psarakos used television to test dolphin self-awareness, concluding their evidence suggested self-awareness rather than social behavior.
1996: Fraser's Dolphin Recorded in the UK
In 1996, Fraser's dolphin, typically found in tropical waters, was recorded in the UK for the first time, suggesting a shift in dolphin distribution possibly due to changing climate conditions.
1998: Pacific White-Sided Dolphin Increase in Canada
From 1984 to 1998, the Pacific white-sided dolphin had an increase in occurrence on the west coast of Canada, indicating a possible range shift due to changing environmental conditions.
1999: Captive-Born Orcas
By 1999, about 40% of the 48 animals on display in the world were captive-born, a significant increase compared to previous decades.
1999: Tilikum's Second Incident
In 1999, Tilikum played a role in the death of three people in three different incidents.
2000: Dolphins Trained to Kill Sold to Iran
In 2000, press reports surfaced claiming that dolphins, previously trained to kill by the Soviet Navy, were sold to Iran.
2003: White-Beaked Dolphin Decreased in Scotland
From 1992 to 2003, white-beaked dolphins in northwest Scotland decreased while common dolphins (local to warmer waters) have increased, indicating a range shift possibly due to warming waters.
2003: Short-Beaked Common Dolphin Subpopulation Endangered
In 2003, the short-beaked common dolphin Mediterranean subpopulation was deemed endangered due to reduced prey resources, highlighting the impact of environmental changes on dolphin populations.
May 2005: Discovery of Tool Use in Indo-Pacific Bottlenose Dolphins
In May 2005, in Australia, Indo-Pacific bottlenose dolphins were found teaching their young to use sponges to protect their snouts while foraging. This discovery highlights cultural transmission and tool use in dolphins.
2005: Dolphin-Assisted Therapy Study
In 2005, a study suggested dolphins were an effective treatment for mild to moderate depression. However, this study and the concept of dolphin-assisted therapy (DAT) faced criticism for methodological flaws and a lack of evidence supporting its legitimacy or superiority over other forms of therapy.
October 2006: Bottlenose Dolphin with Vestigial Fins Captured
In October 2006, a bottlenose dolphin captured in Japan had small fins near its genital slit, believed to be a pronounced development of vestigial hind limbs, providing evidence of evolutionary history.
2006: Yangtze River Dolphin Survey
A 2006 survey found no individuals of the Yangtze river dolphin. The species now appears to be functionally extinct.
2007: Discovery of Spindle Neurons in Dolphin Neocortex
Prior to 2007, elongated spindle neurons, previously only known in hominids, were found in the neocortex of many dolphin species. These cells are linked to social conduct, emotions, judgment, and theory of mind.
2009: Mycenaean City Excavations
During the 2009 excavations of a major Mycenaean city at Iklaina, a striking fragment of a wall painting came to light, depicting a ship with three human figures and dolphins.
2010: Tilikum's Third Incident
In 2010, Tilikum played a role in the death of three people in three different incidents.
2011: Increased Tail-Walking Among Dolphins
By 2011, up to 12 dolphins were observed tail-walking, but only females appeared to learn the skill, indicating a possible social or learned behavior among female dolphins.
2014: Dolphin Deaths in Queensland Shark Control
Since 2014, at least 32 dolphins have been killed in Queensland due to the "shark control" program, illustrating the ongoing threat to dolphin populations.
2017: Number of Orcas in Captivity
As of 2017, there were only 60 captive orcas being held in aquaria.
2017: Tilikum's Death
In 2017, Tilikum died at SeaWorld. Tilikum played a role in the death of three people in three different incidents.
2018: Study on Dolphin Tail-Walking
A 2018 study suggested the spread of tail-walking behavior in dolphins is surprising, as it brings no apparent advantage and is very energy-consuming.
October 2021: Dolphin Observed Tail-Walking
In October 2021, a dolphin was observed tail-walking over a number of hours.
