Platypus (Ornithorhynchus anatinus) Fact Sheet: Behavior & Ecology

Mainly active at night

(Serena 1994; Grant 2015)

• Shelter in burrow during the day (Serena 1994; Grant 2015)
  • Emerge from burrow in late afternoon
  • Re-enter burrow in the early morning
  • Serena (1994) found that platypuses in Victoria spent 11-17 hours in burrow
  • Sometimes active during the day (e.g., see Otley 2001, Fig. 4)
• Feeding
  • See Feeding
• Pregnant females
  • Spend time building nest, nursing and sleeping with young, and foraging (Holland and Jackson 2002)
• Do not hibernate (Nicol 2017)
  • May be inactive for extended periods (Fleay 1994b; Serena 1994)

Behavior patterns

• Platypuses mainly dive to obtain food (Grant 2015)
• Generally limited to shallow water (Grant 2015)
  • Prefer depths of 1-5 m (3-16 ft)
  • Occasionally dive deeper than 8 m (26 ft) (Bethge et al. 2003)
    • Grant (2007) notes one exceptional individual caught in a net set at 30 m (98 ft)
• Make multiple short dives (Bethge et al. 2003; Grant 2015, except as noted)
  • On average, 75 dives per hour when feeding
  • Most dives last 20-40 seconds
    • Active dives up to 59 seconds
    • Can hold breathe up to 11 minutes, if under submerged object and remain still (i.e., using minimal oxygen) (Grant 2007)
  • Only spend 10-15 seconds at surface between dives
• Dive down at about a 45° angle (Kruuk 1993)
  • Propelled by forelegs
  • Make little disturbance on water’s surface
    • Also see “Swimming” in Locomotion
• At the surface, simultaneously catch breath and chew food caught on previous dive (Kruuk 1993)
  • Also see “Head, bill, and mouth” in General Appearance
• Diving and foraging are energetically demanding (Grant 2015)
  • Must produce body heat to compensate for heat lost to cold water
  • Air bubbles trapped in fur make a platypus’ body more buoyant
• Eyes, nostrils, and ears closed while diving (Grant 2015)
  • How platypuses detect food and underwater objects is not fully understood (Grant 2015)
    • Mechano- and electroreceptors thought to play important roles
    • Move head and bill from side to side while diving

Adaptations

• Low metabolism (Fish et al. 1997; Grant 2015)
• Lower heart rate while diving (Evans et al. 1994, except as noted)
  • 140-230 beats per minute swimming at surface
  • 10-120 beats per minute while diving
    • Up to 300-400 beats per minute before/after dives (Grant 2007)
• Lungs relatively large (Grant 2015)
• Blood carries a lot of oxygen (Evans et al. 1994; Grant 2015)
• Can quickly inhale a large quantity of air (Evans et al. 1994; Grant 2015)
• Blood vessels around pelvis reduce blood flow to hind body, increasing the amount of oxygen available to the brain (Booth and Connolly 2008)
• Also see Physical Characteristics
• Also see Locomotion

General

• Types of burrows (Serena 1994)
  • Resting
    • Used by males and non-breeding females while resting and for protection
  • Nesting/nursery
    • Used by breeding females and their young
• Benefits
  • Protection from predators (Grant 2015)
  • Buffer against temperature extremes (Grant 2015)
• Habitat and structure
  • Burrows usually made in earthen stream banks (Serena 1994; Grant 2015; Woinarski and Burbidge 2016)
    • Sometimes in stream debris or under low, dense vegetation
  • Entrances made at or just below water level (Serena 1994)
    • Under overhanging banks or vegetation
    • Single or multiple entrances
  • Tunnels lead to oval-shaped chambers (Serena 1994)
  • Also see “Nesting burrows” in Parental Care
• Use by platypuses (Serena 1994, except as noted)
  • Typically enter and exit burrow once a day
  • May rest at more than one burrow location
  • Observations of burrow sharing
  • Juveniles observed to use multiple burrows (Thomas et al. 2019)

Home range

• Home range shape: linear (along a stream) (Grant 2015)
• Length varies
  • Males: 200 m to 15 km (0.1 to 9.3 mi) (Grant 2015)
  • Females: < 2 to 4.5 km (< 1 to 2.8 mi) (Serena et al. 1998)
• Females may show strong residency patterns (Bino et al. 2015)
  • Feed near nesting burrow (Serena and Williams 2012a)
• Adult males have larger, more exclusive home ranges compared to females and juveniles (Serena 1994; Serena and Williams 2012a; Grant 2015, except as noted)
  • Need more food due to larger body size
  • May move more than 10 km (6 mi) in a single night (Serena et al. 1998)
    • More resident than juvenile males (Bino et al. 2015)
  • Larger range provides access to more females during breeding
• Home ranges of males overlap less during breeding season (Grant 2015)
  • Appear to exclude and avoid each other

Dispersal

• In most cases, use waterways to disperse (Furlan et al. 2013)
  • Can disperse over land (Kolomyjec et al. 2009; Gongora et al. 2012)
    • Move between river systems, promoting genetic exchange
      • Thought to be more common in juveniles and migrant individuals
    • May be found considerable distances from water, especially during drought conditions (Grant 2007)
    • Challenges while far from water
      • Exposed to high air temperatures
      • High energetic costs
      • Higher risk of predation (mainland Australia)
• In Victoria, juveniles begin dispersing at about 7-8 months of age (3-4 months after emerging from nesting burrow) (Serena and Williams 2012b; Martin et al. 2014)

Social system

• Appear to be solitary outside of breeding season (Grant 2015)
  • No evidence of long-term pairs or family groups (Grant 2015)

Smell/olfactory communication

• Scent glands present on both sides of neck (Grant 2015)
  • Produce musky odor
    • Secretions increase during breeding season
  • In managed care, mark objects (e.g., logs, rocks) by rubbing against them
• Smell and/or taste stimuli may be processed more by vomeronasal organ (mouth) than by nostrils (Grant 2015)

Tactile communication

• Various interactions between mother and young (Grant 2015)
• Also see Courtship

Vocalizations

• May make a low-pitched growl when disturbed, feel threatened (Sharpe 1994a; Rakick et al. 2001; Grant 2015), or are handled by an unfamiliar keeper (Jackson 2003)
• In wild individuals, no evidence to date of platypuses using vocalizations to communicate with other platypuses (Grant 2015)
  • Grant (2007) notes noises made by nestlings (captured during documentary filming)

Defense

• When alarmed, swim away or dive, and make a splashing sound (Fleay 1944b; Grant 2015)
  • Not known if this is a warning communication to other platypuses

Aggression

• Adult males more aggressive during breeding (Grant 2015)
• Spurs thought to be used to fight with rival males during breeding (Wong et al. 2012; Grant 2015)
  • Size of venom gland increases during breeding
• Envenomation rarely observed (Whittington and Belov 2014)
  • Wrap hind legs around opponent and drive in sharp spurs
• Temporary limb paralysis, and later, stiffness or edema can occur when a male stings another male (Temple-Smith 1973)
  • Venom not fatal to other platypuses
  • May deter other males from competing for mates or territory

Access to females

• Males appear to defend home ranges of females to gain mating access (Serena and Grant 2017)

Sleeping

• Platypuses often sleep curled up (Grant 2007)
  • Broad tail covers underside of body to conserve body heat
• Experience rapid eye movement (REM) sleep, similar to other mammals (Siegel et al. 1999)
  • Associated with eye movement, muscle twitching, and possibly dreaming
  • In platypus, forebrain not involved, as in adult humans

Feeding

• Platypus and riverine fish (e.g., Galaxias, Gambusia holbrooki, and introduced carp, Cyprinus carpio) may compete for similar prey (Grant 2007; Klamt et al. 2016)

Relationship with humans

• Wild platypuses seldom interact with humans (Grant 2015)
  • Small
  • Mainly nocturnal
  • Cryptic—burrow
• Not often seen in the wild, even by Australians living in rural areas (Grant 2007; Grant 2015)
  • Sometimes seen if sick, injured, or accidentally caught in fishing gear
• Humans infrequently spurred by platypuses in the wild (Grant 2015, and as noted)
  • Humans and platypuses rarely in close proximity to each other (Grant 2007)
    • Exceptions
      • Anglers
      • Construction crews
      • Scientific researchers
  • Symptoms resulting from envenomation (Fenner et al. 1992; Torres et al. 2007)
    • Pain
      • Sometimes severe
      • Can last weeks to months
    • Swelling
      • When prolonged, can affect limb function
    • Tenderness
    • Fever
    • Nausea
    • Sometimes, a decrease in blood pressure in humans
  • No human fatalities reported (Whittington and Belov 2014)
  • Treatment
    • No antivenom (antivenin) available (Fenner et al. 1992; Koh et al. 2009)
    • Main treatment is for pain relief, by stopping nerve transmission (Fenner et al. 1992)
    • See Whittington and Belov (2014) for detailed discussion of symptoms and venom composition

Walking

• Legs positioned to side of body (Grant 2007)
• Webbing on forefeet folds under foot for easier walking and to expose claws (Grant 2015)

Swimming

• Can swim 0.7-2.4 kph (0.4-1.5 mph) (Grant 2007; Grant 2015)
  • Speeds of up to 3.6 kph (2.2 mph) reported by Fish et al. (1997)
• Unique swimming mode (Fish et al. 1997; Grant 2015)
  • Alternately thrust forelimbs (“rowing”)
    • Range of stroke more similar to that of a sea lion than that of a polar bear
    • Webbing extends past claws for faster swimming
• Rear feet used as rudders (Grant 2015)
• Also see Diving

Researchers use fyke nets to collect platypuses at night, when these animals are most active.

Because platypuses are nocturnal, aquatic, cryptic burrowers, much is still to be learned about their behavior and ecology.

Researchers must hold wild platypuses by the tail to avoid being envenomated by the spurs on this animal's hind feet.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.