 Male echidnas have non-venomous spurs on the hind feet.The neocortex makes up half of the echidna's brain, compared to 80% of a human brain.Due to their low metabolism and accompanying stress resistance, echidnas are long-lived for their size; the longest recorded lifespan for a captive echidna is 50 years, with anecdotal accounts of wild individuals reaching 45 years.