Kalmar "homeothermic" tana nufin iyawar kwayoyin halitta don kiyaye yawan zafin jiki na jiki, ba tare da la'akari da yanayin yanayin waje ba. Ana amfani da ita a cikin mahallin dabbobi masu jinni, kamar tsuntsaye da dabbobi masu shayarwa, waɗanda ke da ikon daidaita yanayin zafin jikinsu a cikin kunkuntar kewayo, yawanci a kusa da digiri 37 Celsius (digiri 98.6 Fahrenheit). Wannan tsarin sarrafa kansa yana ba da damar kwayoyin halitta don daidaitawa da aiki yadda ya kamata a cikin yanayi daban-daban na muhalli.