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Galapagos Giant Tortoises (Chelonoidis spp.) Fact Sheet: Taxonomy & History

Taxonomic History and Nomenclature

Taxonomic history

  • Many taxonomic changes through decades of scientific study; still an ongoing debate
  • Change to genus name
    • Before Chelonoidis, Giant Galápagos Tortoises (GGTs) were previously considered to part of genuses Geochelone and Testudo (Fritz and Havas 2006; Turtle Taxonomy Working Group; van Dijk et al. 2014)
    • Other South American tortoises also included in Geochelone
  • Many of today’s recognized species were previously considered subspecies of Chelonoidis niger (Fitzinger 1835) (Fritz and Havas 2006; Turtle Taxonomy Working Group; van Dijk et al. 2014)
    • Elevated to full species level in light of molecular evidence published by Le et al. (2006)
  • Historically, taxa grouped by geography
    • Which island or volcano a group of tortoises, with similar characteristics, lived on
  • Originally, as many as 14 species recognized (under genus Testudo) (Van Denburgh 1914; Poulakakis et al. 2015)
  • Genetics and morphology used in Giant Galápagos Tortoise (GGT) classification today

Current taxonomy, as of October 2015 (Linda Cayot, personal communication, 2016; prepared by Galápagos Conservancy and Galápagos National Park scientists for publication in a book by Tui de Roy, and future scientific literature)

  • The following taxonomy is used by many GGT scientists.
    • Species are listed alphabetically, with island location noted
  • Extant species (in alphabetical order by species name)
    • Chelonoidis becki (Rothschild 1901) – Wolf Volcano, Isabela Island
    • Chelonoidis chathamensis (Van Denburgh 1907) – San Cristóbal Island
    • Chelonoidis darwini (Van Denburgh 1907) – Santiago Island
    • Chelonoidis donfaustoi (Poulakakis, Edwards, and Caccone 2015) – Eastern Santa Cruz Island
      • Previously considered part of Chelonoidis porteri
    • Chelonoidis duncanensis (Garman in Pritchard 1996) – Pinzón Island
    • Chelonoidis guntheri (Baur in Pritchard 1971) – Sierra Negra Volcano, Isabela Island
    • Chelonoidis hoodensis (Van Denburgh 1907) – Española Island
    • Chelonoidis microphyes (Günther 1875) –  Darwin Volcano, Isabela Island
    • Chelonoidis porteri (Rothschild 1903) – Western Santa Cruz Island
    • Chelonoidis vandenburghi (DeSola 1930) – Alcedo Volcano, Isabela Island
    • Chelonoidis vicina (Günther 1875) – Cerro Azul Volcano, Southern Isabela Island
  • Extinct species (in alphabetical order by species name)
    • Chelonoidis abingdonii (Günter 1877) (extinct, 2012) – Pinta Island
      • Hybrids with partial C. abingdonii ancestry found on Wolf Volcano, Isabela Island
    • Chelonoidis elephantopus (Quoy and Gaimard 1824) (extinct, ca. 1850) – Floreana Island
      • Hybrids with partial C. elephantopus ancestry found on Wolf Volcano, Isabela Island
    • Chelonoidis phantastica (Van Denburgh 1907) (extinct, ca. 1970) – Fernandina Island
      • Based on a single, historical specimen
      • May not have been a distinct species (Poulakakis et al. 2012)
      • Extinction likely caused by volcanic activity (Márquez et al. 2007)
    • Undescribed species (extinct, mid-1800s) – Santa Fe Island
      • Most closely related to Española Island GGTs (galapagos.org)
      • Santa Fe Island repopulated with Española Island GGTs, beginning in 2015
  • For information on conservation status and repatriation programs, see Population & Conservation Status.

 Previous taxonomy, as of 2014 (Turtle Taxonomy Working Group: van Dijk et al. 2014)

  • Reclassification of the former Chelonoidis nigra species complex
    • Previous subspecies elevated to full species level based on genetic evidence (Poulakakis et al. 2012)
      • Found to be independent evolutionary units
  • Spanish and English names for each species provided below
    • Many Latin species names refer to English names for the Galápagos Islands (see Nomenclature, below)
  • Extant species
    • Chelonoidis becki (Rothschild 1901) – Volcan Wolf Giant Tortoise
    • Chelonoidis chathamensis (Van Denburgh 1907) – San Cristobal Giant Tortoise, Chatham Island Giant Tortoise
    • Chelonoidis darwini (Van Denburgh 1907) – Santiago Giant Tortoise, James Island Giant Tortoise
      • Included synonymized taxa
        • C. n. wallacei
    • Chelonoidis duncanensis (Garman in Pritchard 1996) – Pinzon Giant Tortoise, Duncan Island Giant Tortoise
      • Included synonymized taxa
        • C. n. ephippium
    • Chelonoidis hoodensis (Van Denburgh 1907) – Española Giant Tortoise, Hood Island Giant Tortoise
    • Chelonoidis porteri (Rothschild 1903) – Western Santa Cruz Giant Tortoise, Indefatigable Island Giant Tortoise
    • Chelonoidis donfaustoi (Poulakakis, Edwards, and Caccone 2015) – Eastern Santa Cruz Giant Tortoise
      • Previously considered part of Chelonoidis porteri
    • Chelonoidis vicina (Günther 1875) – Southern Isabela Giant Tortoise, Albemarle Island Giant Tortoise
      • Included synonymized taxa
        • C. n. guentheri
        • C. n. microphyes
        • C. n. vandenburghi
  • Extinct species
    • Chelonoidis abingdonii (Günter 1877) (extinct, 2012) – Pinta Giant Tortoise, Abingdon Island Giant Tortoise
    • Chelonoidis phantastica (Van Denburgh 1907) (extinct, ca. 1970) – Fernandina Giant Tortoise, Narborough Island Giant Tortoise
      • Based on a single, historical specimen
      • May not have been a distinct species (Poulakakis et al. 2012)
    • Chelonoidis nigra (Quoy and Gaimard 1824) (extinct, ca. 1850) – Floreana Giant Tortoise, Charles Island Giant Tortoise
    • Undescribed species (extinct, mid-1800s) – Santa Fe Island
      • Most closely related to Española GGTs (galapagos.org)

 Nomenclature

  • Genus
    • Chelonoidis
      • From the Greek word for "turtle" (Olson and David 2014)
  • Species names
    • Many refer to the English names for islands in the Galápagos (Pritchard 1998)
      • Used by Van Denburgh to name original species (Van Denburgh 1914)
      • Islands often named for explorers
        • Examples: darwini for Charles Darwin, hoodensis for Captain Hood
  • Recent species named
    • donfaustoi
      • “Named in honor of Fausto Llerena Sánchez, who devoted 43 years of service (1971-2014) to giant tortoise conservation as a park ranger with the Galápagos National Park Service” (Poulakakis et al. 2015).
      • See Poulakakis et al. (2015), “Etymology,”  to read more about “Don Fausto’s” contribution to giant tortoise biology and conservation.

Synonyms

  • Genus names (Olson and David 2014)
    • Geochelone (elephantopus)
    • Testudo (elephantopus)
  • Species names

Common names (Gibbons and Greene 2009; Orenstein 2012)

  • Galápagos Tortoises, Galápagos Giant Tortoises, Giant Galápagos Tortoises (English)
  • Tortugas gigante de los Galápagos (Spanish)
  • “Tortoise”
    • Usage varies across the world
    • In this fact sheet, refers to terrestrial turtles in the family Testudinidae
  • “Turtle”
    • Usage varies across the world
    • Often refers to both aquatic and terrestrial species of the order Testudines
  • Historical references, mostly used by sailors and merchants
    • Terrapins, turpin, turpine, tarpain, turupin, terapen

Evolutionary History

Diversity of tortoises

  • Family Testudinidae (“tortoises”) (Le et al. 2006; Orenstein 2012, and as noted)
    • Includes about 60 species (Turtle Taxonomy Working Group: van Dijk et al. 2014)
      • Approximately 20% of all living turtles
    • Live on most continents (Hansen et al. 2010)
      • Except Australia and Antarctica
    • Terrestrial, land-dwelling
    • Slow-moving
    • Most (but not all) with domed, rigid shell
      • Lower surface-to-volume ratio
        • Adaptation to cope with dry conditions
      • Upper carapace and lower plastron connected by bridge
      • Carapace fused to vertebrae (backbone) and ribcage
    • “Elephantine” legs and feet
      • Resemble limbs of elephants
    • Connotation of limbs being bulky, hefty, clumsy, awkward
  • Closest relatives of tortoises
    • Geoemydidae (Asian river turtles)
    • Emydidae (American pond turtles)

Evolutionary history of modern tortoises (Family Testudinidae)

  • Emerged ~ 55 mya (Hansen et al. 2010)
  • Part of the oldest reptile lineage (Hansen et al. 2010)
  • More closely related to crocodilians and birds than to lizards and snakes (Crawford et al. 2012)
  • Origins: in Asia during late Mesozoic or early Cenozoic (Le et al. 2006)
    • Testudinids soon dispersed to Africa, Europe, and North America
      • Based on fossil evidence from the Cretaceous, Paleocene, and early Eocene
    • Most extant genera have African ancestries (Gerlach et al. 2006; Le et al. 2006; Hansen et al. 2010)
      • Dispersed from Africa to South America
        • Likely drifted or rafted with westward ocean currents
          • Can float while extending their head to breathe
          • Able to survive without food or freshwater for months
  • Extinctions: At least 36 species of large and giant tortoises since the late Pleistocene (Hansen et al. 2010)
    • Majority occurred on islands
    • Most due to human overhunting and impacts

 GGTs colonize a number of Galápagos Islands

  • Arrived in the Galápagos archipelago approximately 3.2 mya (Pliocene) (Poulakakis et al. 2012)
    • Drifted from South America (Poulakakis et al. 2012)
      • Likely drifted with westward ocean currents
    • Evolved to large size before dispersing from the mainland (Caccone et al. 1999; Orenstein 2012)
      • GGT lineage split from its closest South America relatives 6-12 mya, before the formation of the oldest extant Galápagos Island (Caccone et al. 1999)
    • Some, but not all islands colonized (Standford 2010)
    • Oldest islands, San Cristobal and Española, colonized first
    • First divergence within the Galápagos approximately 1.74 mya (Poulakakis et al. 2012)
      • Result of dispersing from older to younger islands
    • Colonization not always linear (dispersing from older to younger islands) (Poulakakis et al. 2012)
      • Central Galápagos Islands once geologically combined in a single landmass (Poulakakis et al. 2012)
        • Ex. Northern and southern Isabela once two separate islands, now connected by young lava formations
      • Some GGT populations could interbreed, until islands separated
  • Getting from island to island
    • Drifted on currents (Hansen et al. 2010)
    • Not good swimmers, but float well (Gerlach et al. 2006)
      • Slow metabolism (Hansen et al. 2010)
      • Can go without food or freshwater for up to 6 months (Caccone et al. 2002)
    • Transported by humans, especially 17th to 19th centuries (Thorbjarnarson et al. 2000; Poulakakis et al. 2012)
      • Whalers and buccaneers used as source of fresh meat and oil
      • Left GGTs at different islands, or occasionally dropped overboard, if needed to lighten their shiploads
      • Charles Darwin reported single vessels that took up to 700 GGTs at a time (Poulakakis et al. 2008)
  • Unique evolutionary clades on most islands (Poulakakis et al. 2008; Chiari et al. 2009; Poulakakis et al. 2015, except as noted)
    • Genetically and sometimes morphologically distinct
    • Represent single colonization events
    • Little or no genetic exchange with other islands
    • Classic example of rapid evolutionary radiation (Garrick et al. 2015)
  • Multiple genetic lineages on some islands
    • Isabela (Edwards et al. 2014)
    • Santa Cruz (Poulakakis et al. 2015)
    • Populations geographically isolated by mountains, volcano formations, or lava flows (Garrick et al. 2014; Poulakakis et al. 2015)
      • Represent colonizations from more than one neighboring island (Chiari et al. 2009; Poulakakis et al. 2012; Poulakakis et al. 2015)
        • Individuals more closely related to tortoises on neighboring islands than to another species that lives on its same island
    • When not isolated, evidence of lineages fusing together (Garrick et al. 2014)
      • Likely a recurrent phenomenon
  • Domed and saddleback shell shapes seem to have evolved multiple times in the Galápagos Archipelago (Poulakakis et al. 2008; Chiari et al. 2009)

Closest living relative

  • Chaco tortoise, Chelonoidis chilensis (Caccone et al. 1999)
    • Small tortoise
    • Occurs in South America

GGT extinctions

  • Several species extinct due to hunting by humans (Thorbjarnarson et al. 2000; Poulakakis et al. 2008)
  • Chelonoidis abingdonii – Pinta Giant Tortoise (Edwards et al. 2013)
    • Recent extinction
    • Last purebred Pinta GGT named "Lonesome George"
      • Died in captivity on 24 June 2012
      • Signified the extinguishing of a species
      • Has become a conservation icon
      • His preserved body now part of an interpretive exhibit at the Charles Darwin Research Station
    • Select, hybrid GGTs reintroduced to Pinta
  • Chelonoidis elephantopus – Floreana Giant Tortoise
  • Chelonoidis phantastica – Fernandina Giant Tortoise
  • GGTs on Santa Fe
    • Historical extinction of an undescribed species
      • Most closely related to Española GGTs (galapagos.org)
    • 200 young Española GGTs (C. hoodensis) reintroduced in 2015 (Tapia 2015)
  • Some genetic diversity of extinct species maintained in extant species (Poulakakis et al. 2008)
    • E.g., descendants of extinct Floreana GGTs on Isabela
    • Genetic material also conserved in captive populations (e.g., zoos) (see Benavides et al. 2012)
  • Captive breeding and reintroduction/repatriation programs for some species (Linda Cayot, personal communication, 2016)
    • C. hoodensis
    • C. guntheri
    • C. vicina
    • C. duncanensis
    • C. chathamensis
    • C. darwini
    • Pinta and Santa Fe

Cultural History

History

  • 1535: First record of humans visiting the Galápagos (Thorbjarnarson et al. 2000)
    • Fray Tomás de Berlanga impressed by the tortoises
      • Names the islands after them (galápagos = tortoises in old Spanish)
  • Late 1600s-1700s: overhunting by buccaneers (MacFarland et al. 1974)
  • Late 1700s-late 1900s: overhunting by whalers, sealers, merchants, and crews of naval ships (MacFarland et al. 1974; Thorbjarnarson et al. 2000; Powell and Caccone 2006)
    • Live GGTs stored in hulls of ships
      • Valuable source of fresh meat, before refrigeration
      • Used fat to make oil
        • Substituted for butter or shortening
    • Hundreds of GGTs taken at a time
    • Collection of “easier to carry tortoises” may have resulted in biased take of female GGTs
    • At least 40,000 to 200,000 GGTs killed
  • 1800s: several settlements established (Thorbjarnarson et al. 2000; Powell and Caccone 2006)
    • GGTs killed for meat, fats, and oil
    • Political prisoners from Ecuador survive mainly on GGT meat
    • Domestic animals introduced to the islands
    • Natural habitat converted to pasture and farmland
  • 1835: Charles Darwin and the rest of the Beagle crew spend five weeks in the Galápagos (Poulakakis et al. 2008; Sulloway 2009; Orenstein 2012, and as noted)
    • Darwin transports three young GGTs home to London (Standford 2010)
      • Named Tom, Dick, and Harry
    • 30 other live GGTs stored as food for the journey home (Standford 2010)
    • 1839: Voyage of the Beagle published
      • Darwin reflects on how local Spaniards were able to recognize tortoises from the different islands
        • Later, also credits vice-governor of the islands, Nicholas Lawson, with this understanding
      • Inspires Darwin to write a passage suggesting the possibility of evolutionary change
    • In the wider culture, GGTs become an exemplar of Darwin’s theory of natural selection
      • However, Galápagos finches, not tortoises, mentioned in The Origin of Species
      • Likely influenced his thinking about biogeography (Powell and Caccone 2006)
    • For a re-tracing of Darwin’s excursion on Santiago Island, see Sulloway (2009)
  • California Gold Rush (Conrad et al. 2015; Conrad 2016)
    • GGTs taken from the Galápagos Islands
      • Some eaten on the journey to California (fresh food supply)
      • Many sold, alive, in San Francisco
    • One newspaper reported a schooner arriving with 500 “terrapin” (tortoises and sea turtles) onboard (Conrad et al. 2015)
  • 1880s-1930: Expeditions removed at least 600 tortoises from the wild
  • Early 1900s-1960s
    • Fishing activity increases in the Galápagos (MacFarland et al. 1974, except as noted)
      • Tortoises taken for food (Thorbjarnarson et al. 2000)
      • Goats introduced as an additional food source
      • Mid-1920s: Santa Cruz colonized
        • At least 1,000-2,000 tortoises killed by oil hunters (Thorbjarnarson et al. 2000)
        • Many feral animals introduced
    • Tortoise oil industry strains GGT populations
    • Cattle ranchers eliminate tortoises from a large area of Isabela
  • 1959: Galápagos National Park created (Thorbjarnarson et al. 2000)
    • Illegal to take GGTs or their eggs from the islands

GGTs in culture and folklore

  • Iconic of the Galápagos (Poulakakis et al. 2015)
    • Represent efforts to conserve the Galápagos’ unique wildlife (Caccone et al. 1999)
  • Guinness Book of Records names Pinta Giant Tortoise, “Lonesome George,” the world’s “rarest living creature”
  • “Harriet,” a GGT living in Steve Irwin’s Australia Zoo, becomes a popular animal attraction
    • Rumored to have been originally collected by Charles Darwin (“Harry”); this is likely false (Powell and Caccone 2006; Orenstein 2012)
  • Beliefs among some local peoples
    • GGT meat provides important nutrients for mothers, after giving birth (Márquez et al. 2007)
      • Has exacerbated poaching of GGTs
  • For an overview of turtles in literature, see Chapter 11 of Turtles: The Animal Answer Guide (Gibbons and Greene 2009)

San Diego Zoo Global

  • San Diego Zoo ambassador Joan Embery appeared with a GGT on The Tonight Show with Johnny Carson (23 January 1976) (Embery and Demong 1980; Lisa Bissi, personal communication 2016)
    • 500-lb tortoise had to be transported to the Los Angeles studio stage using a forklift
  • One of the San Diego Zoo’s GGTs, “Gerty,” was part of the 1941 film Malay (Galápagos Tortoise: San Diego Zoo Animals)
    • The film’s hero, played by Jack Haley, sits on Gerty, mistaking him for a rock
  • Paws, Hoofs, and Wings!, a children’s book
    • Narrated by a famous San Diego Zoo Galápagos tortoise named “Speed”

Documentaries

  • Galapagos 3D – 2014, Nwave Pictures
    • Footage of many Galápagos animals
    • Narrated by David Attenborough and Jeff Corwin
  • Life in Cold Blood: Armoured Giants – 2008, BBC
    • David Attenborough explores the lifestyle of Galápagos tortoises in Part 5 of this series

Books

Art

  • Paintings
    • Galápagos Tortoise, sumi ink on paper – Angie Dixon, sumi painter
  • Photography
    • Pete Oxford, wildlife photographer and Galápagos naturalist

Classification

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia (Laurenti, 1768)

Order: Testudines (Linnaeus, 1758)

Suborder: Cryptodira

Family: Testudinidae (Terrestrial turtles with high domed carapace, elephantine feet) (Batsch, 1788)

Genus: Chelonoidis (Fitzinger, 1835)

Species:

  • Chelonoidis becki (Rothschild 1901) – Wolf Volcano, Isabela Island
  • Chelonoidis chathamensis (Van Denburgh 1907) – San Cristóbal Island
  • Chelonoidis darwini (Van Denburgh 1907) – Santiago Island
  • Chelonoidis donfaustoi (Poulakakis, Edwards, and Caccone 2015) – Eastern Santa Cruz Island
  • Chelonoidis duncanensis (Garman in Pritchard 1996) – Pinzón Island
  • Chelonoidis guntheri (Baur in Pritchard 1971) – Sierra Negra Volcano, Isabela Island
  • Chelonoidis hoodensis (Van Denburgh 1907) – Española Island
  • Chelonoidis microphyes (Günther 1875) –  Darwin Volcano, Isabela Island
  • Chelonoidis porteri (Rothschild 1903) – Western Santa Cruz Island
  • Chelonoidis vandenburghi (DeSola 1930) – Alcedo Volcano, Isabela Island
  • Chelonoidis vicina (Günther 1875) – Cerro Azul Volcano, Southern Isabela Island
  • Chelonoidis abingdonii (Günter 1877) (Extinct, 2012) – Pinta Island
  • Chelonoidis elephantopus (Quoy and Gaimard 1824) (Extinct, ca. 1850) – Floreana Island
  • Chelonoidis phantastica (Van Denburgh 1907) (Extinct, ca. 1970) – Fernandina Island
    • In 2019, discovery of one isolated individual (news story)
  • Undescribed species (Extinct, mid-1800s) – Santa Fe Island

Sources: van Dijk 2014 (Turtle Taxonomy Working Group); Linda Cayot, personal communication, 2016

Late Night Celebrity

a GGT, Johnny Carson, and Joan Embery

January 23, 1976: A 500-pound Galápagos tortoise appeared on the Tonight Show with Johnny Carson and San Diego Zoo ambassador Joan Embery.

Image credit: © San Diego Zoo Global. All rights reserved.

A Symbol of Conservation

Lonesome George

The Guinness Book of Records named "Lonesome George," the last giant tortoise from Pinta Island, the world’s “rarest living creature.”

Since George died in 2012, he has become a powerful symbol of biodiversity conservation.

Image credit: © Galapagos Conservancy and Tim Saxe; photo by Tim Saxe. All rights reserved. Used with permission from the artist and Galapagos Conservancy.

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