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Chinese Giant Salamanders (Andrias spp.) Fact Sheet: Reproduction & Development

Courtship

Mating system (wild populations)

  • Not well known (Ben Tapley, personal communication, 2019)
    • Possibly polygynous (1 male, multiple females) (Liang and Wu 2010; Browne et al. 2014)
      • Eggs at a nest site laid by several females
      • Dominant male fertilizes and defends eggs

Courtship behavior and interlocking

  • Male waits at entrance to breeding den (see “Den preparation,” below) (Nickerson 2004)
    • Allows female to enter den or chases her into den
  • Courtship behaviors (Liang and Wu 2010; Luo, Tong, et al. 2018)
    • Male–female stand side by side with heads touching
    • Male pushes belly of female
    • Male climbs on female’s back or rests head on female’s back
    • Pair postures mouth to mouth
  • As female lays eggs into slight depression, male moves alongside her and releases sperm over egg mass (Laidler and Laidler 1996; Nickerson 2004)

Reproduction

Breeding

  • Sexual maturity
    • Best available estimate is 5 to 6 years old, but possibly up to 8 years old—possibly longer (Cheng 1998; Xiao et al. 2006; Zhang et al. 2017)
      • Not known for most populations (Benjamin Tapley, personal communication, 2019)
  • Breed annually in the wild populations (Xiao et al. 2006)
    • Seasonal progression (Browne et al. 2014, and as noted):
      • Spring to summer: maturation of gonads (May to late July)
        • Initiated by warming water temperatures (Xiao et al. 2006)
      • Summer: spawning (August to mid-September)
        • Corresponds with warmest annual water temperatures (Zhang et al. 2006, as cited by Browne et al. 2014)
      • Early winter: brooding of young and larval development
      • Winter: adults inactive; larvae leave den and shelter in river gravel/debris
  • Some salamander farmers induce reproduction (sperm development, ovulation of eggs) using hormone injections (Xiao et al. 2006)
    • Natural breeding is becoming increasingly common (Benjamin Tapley, personal communication, 2019)

Den preparation

  • Dens are hollows located under rocks or in riverbank (Luo, Tong, et al. 2018)
    • Site where female lays eggs, and male fertilizes eggs and broods young
  • Male prepares den, clearing out sand or gravel from den space to increase den’s size and water depth (Liang and Wu 2010; Luo, Tong, et al. 2018)
    • Uses limbs, tail, and sometimes head
  • Entrance often faces downstream (Nickerson 2004)

Incubation and Hatching

Egg laying

  • Female lays a string of eggs within male’s den (Liang et al. 2004; Luo, Tong, et al. 2018, and as noted)
    • Lays 10 to 100 eggs several times during breeding season
      • Up to approximately 500 eggs per breeding season (Xiao et al. 2006)
    • Eggs then fertilized externally by the male
    • Egg laying and fertilization may be repeated up to 7 times, lasting up to 3 hours
  • Egg description (Cheng 1998)
    • Color
      • Golden yellow or whitish
    • Size
      • Initially, 7 to 8 mm (0.3 in) in diameter
      • After absorbing water, 15 to 20 mm (0.59 to 0.79 in) in diameter

Hatching

  • Larvae description
    • Photo: Dai et al. (2010), Fig. 12
    • Tadpole-like (Nickerson 2004)
      • Gills external
      • Tail well developed
      • At about 2 weeks old, short limbs present
      • See additional description in Liu and Tang (1989)
    • Size (length)
      • At hatching: 2 to 3 cm (0.8 to 1 in) (Tapley et al. 2017)
      • 6 to 8 days after hatching: 3.5 to 4.0 cm (1.4 to 1.6 in) (Liu and Tang 1989)
        • 26 days after hatching: 3.9 to 4.5 cm (1.5 to 1.8 in) (Liu and Tang 1989)
    • Weight
      • Not well reported
      • Liu and Tang (1989) state about 0.30 g at hatching
    • Coloration (Liu and Tang 1989; Dai et al. 2010)
      • First month of age
        • Upperbody bright brown-red
        • Underbody (yolk sac) golden yellow
        • Small black spots cover entire body
      • Older than 1 month
        • Upperbody brown with larger black spots
        • Underbody yellowish white
      • Older than 5 months
        • Upperbody brownish black
        • Underbody dark purplish red
  • In the wild
    • Larvae grow and develop in a stream (Liang et al. 2004)
    • Leave nest at 4 to 5 cm (about 2 in) long (Tapley et al. 2017)
    • Emerge from springs, in populations where adults live in caves (Dai et al. 2010; Browne et al. 2014)
  • Managed care
    • Incubation period
      • Eggs hatch after about 45 (range: 35-50) days (Liu and Tang 1989; Haker 1997)
    • Larvae begin to feed about 30 days later (Haker 1997)
  • Influences on egg development and hatching success:
    • Fertilization rate (C. Yang et al. 2018)
    • Water temperature (Cheng 1998)
    • Water flow (C. Yang et al. 2018)
      • Bacteria may infect eggs if water movement insufficient (especially on farms, where feces contaminate holding areas)

Parental Care

Parental care behaviors

  • Male agitates eggs by fanning tail within or next to egg cluster (Luo, Tong, et al. 2018)
  • Male eats unfertilized or decomposing eggs (Luo, Tong, et al. 2018)
  • Male may guard eggs and larvae for up to 4 months, until young feed independently (Liang and Wu 2010; Browne et al. 2014)
  • Cheng (1998) suggests larvae may be protected by parents for 10 to 15 days
  • Male does not eat until young grow larger (Browne et al. 2014)

Nourishment of young

  • During first month of life, larvae absorb nutrients from yolk sac (Liu and Tang 1989)
    • Gradually begin to eat food
      • Diet not well known (Ben Tapley, personal communication, 2019)
        • In aquaculture, may eat larvae of mosquitos and flies, small aquatic insects, shrimp, etc. (Liu and Tang 1989)
    • Feed mainly at night, similar to adults (Liu and Tang 1989)

Life Stages

Hatchling

  • Larvae remain in nest/den for up to 4 months (Browne et al. 2014)
    • Guarded by male
  • Large larvae shelter in more exposed sites, outside of den: under small rocks and in river debris (Browne et al. 2014)
    • Still avoid light (Liu and Tang 1989)
    • Possibly shelter within parents’ den at night (Cheng 1998)
  • At about 6 months, larvae begin to shed skin (once a month or more) (Liu and Tang 1989)
    • Larvae may consume the shed skin
  • See “Hatching” in Incubation and Hatching
  • Characteristics of growth and development: see Liu and Tang (1989), Table 3

Juvenile

  • Weight at 1 year old: 10 to 30 g (0.3 to 1 oz) (managed care) (Liu and Tang 1989)
  • Transition from free-swimming larva to bottom-dwelling adult (Laidler and Laidler 1996)
    • Rate of development influenced by water temperature and food availability
  • Metamorphosis
    • Gills degenerate at 2 to 3 years of age, as lungs develop (Cheng 1998; Heiss et al. 2013; Su et al. 2018)
    • Head and mouth structures change (Heiss et al. 2013)
    • Digestive tract develops distinct structures (Zhang et al. 2018)
  • Diet
    • Appears to shift to shrimp and crabs at about 3 to 4 years old (Zhang et al. 2018)

Longevity

Maximum lifespan not yet established

  • Thought to live 50 to 60 years or longer, based on longevity of similar species (Nickerson 2004; Browne et al. 2014; AnAge 2019)
  • At least 25 years in managed care (ZIMS 2019)
    • Not well documented

Mortality and Health

Survival rates

  • Cheng (1998) reports a hatching success rate of 30% (wild population)
  • Liu and Tang (1989) report a 1-year survival rate as high as 91% (managed care)

Predators

  • Juveniles and adults
    • Potentially, mountain carnivores
      • Eurasian otter, Lutra lutra (Zhang et al. 2017)
      • Red fox, Vulpes vulpes (Zheng and Wang 2010)
      • Siberian weasel, Mustela sibirica (Zheng and Wang 2010)
      • Hog badger, Arctonya collaris (Zheng and Wang 2010)

Diseases (non-comprehensive list)

  • Infectious diseases and bacterial infections prevalent in Chinese giant salamander aquaculture (e.g., Zhou et al. 2013; Meng et al. 2014; Cunningham et al. 2016; Z.-Y. Chen et al. 2018)
  • Ranaviruses are the main diseases of concern (Geng et al. 2011; Chen et al. 2013; Zhou et al. 2013; Geng et al. 2016; Z.-Y. Chen et al. 2018; Meng et al. 2018, and as noted)
    • First reported by Geng et al. (2011)
    • Infections often fatal; cause substantial losses on farms
      • High mortality (60 to 95%) during outbreaks on farms
        • Juvenile mortality higher than adult mortality
        • Larval mortality also high (Meng et al. 2014)
      • Sick individuals typically die 1 to 2 weeks after infection
        • Up to 5 weeks, according to Geng et al. (2016)
    • Symptoms (Meng et al. 2014)
      • Juveniles and adults (Cunningham et al. 2016)
        • Swelling, bleeding, ulcers, and necrosis/hemorrhaging of various tissues and organs
        • Also lethargy, vomiting, bloody stools, and weight loss
      • Larvae (Meng et al. 2014)
        • Lethargy
        • Swelling
        • Hemorrhaging
    • No widespread treatment yet available (Z.-Y. Chen et al. 2018)
      • Some success in some early vaccines (e.g., Z.-Y. Chen et al. 2018)
  • Ranaviruses reported for some wild populations (Dong et al. 2011)
    • Not well studied

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