Nurse sharks have the simplest type of tooth arrangement found in sharks. This means that there is no overlapping between the teeth, and that forward movements of teeth leading to shedding does not depend on other teeth. With sharks that have many overlapping teeth, the replacement of teeth cannot take place until the outer blocking teeth are lost. Young Nurse sharks can replace their teeth quicker than adults. Also, teeth replacing occurs faster in summer, when water temperatures are higher. Averaging 2.2-2.7 metres (7.2-9 feet) in total length, and weighing 75-105 kg (165-232 pounds), adult females reach a larger size than adult males which are around 2.1-2.6 metres (7-8.5 feet) long, and weigh around 90-120 kg (198-265 pounds). Females reach maturity at about 2.3 metres (7.6 feet), and males reach maturity at about 2.1 metres (7 feet). New-born Nurse sharks range in length from 28 to 30 cm (11 to 12 inches), with growth rates of 13 cm (5 inches) and 2.3 kg (5 pounds) per year. Once the Nurse sharks reach maturity, their growth rates usually become much lower. 