The nurse shark, Ginglymostoma cirratum, is a common species found resting on the seafloor in tropical and subtropical waters across the Atlantic and Eastern Pacific oceans. This bottom-dwelling shark is often found tucked into crevices or lying still on the sand during the day. Its wide distribution and preference for shallow, coastal habitats make it a frequent subject of curiosity, especially concerning its substantial body size.
Average Length and Weight of Adult Nurse Sharks
Adult nurse sharks commonly reach lengths between 7.5 and 9 feet, placing them among the larger shark species. These mature individuals possess a stocky, powerful build, translating to a considerable average weight. A healthy adult usually weighs between 200 and 330 pounds.
Females exhibit sexual dimorphism, generally growing larger than their male counterparts. Females commonly attain greater lengths, maturing at approximately 7.5 to 8 feet, with some individuals surpassing 9 feet. Males tend to reach sexual maturity at a slightly smaller size, around 7 feet in length.
Record-Breaking Dimensions
While the average adult size is impressive, the absolute maximum dimensions documented for the nurse shark represent rare outliers. The scientifically verified maximum length for Ginglymostoma cirratum is just over 10 feet, specifically recorded at 3.08 meters. This measurement is considered the reliable upper limit based on modern, verifiable records.
Historical accounts have sometimes suggested far greater dimensions, with unverified reports claiming lengths of up to 14 or even 15 feet. These older reports are now widely considered to be exaggerations or misidentifications of other species. Similarly, while a weight of 330 pounds is typical for a large individual, the historically cited maximum weight of 730 pounds is likely inflated and not supported by current scientific data.
The largest confirmed specimens, therefore, measure only slightly more than 10 feet long. These individuals are exceptional in size and significantly exceed the length of the vast majority of nurse sharks encountered in the wild. A female that was one of the largest scientifically examined weighed approximately 252 pounds, highlighting the gap between measured reality and historical claims.
From Pup to Full Size
The journey of the nurse shark from birth to its full adult size is a slow and lengthy process, characteristic of many long-lived shark species. Nurse shark pups are born relatively large, measuring between 10 to 12 inches in length. They are born fully developed, often in litters of 20 to 30 young, ready to navigate their shallow water habitats.
The initial growth rate is modest, with young sharks gaining around 5 inches and a few pounds each year. This slow growth is maintained for many years before the sharks reach reproductive maturity.
Males typically take 10 to 15 years to become sexually mature, while females require an even longer period, often between 15 and 20 years. This delayed maturity means the sharks spend over a decade growing before they can reproduce.
Once maturity is reached, the growth rate slows even further, though the shark continues to increase in size throughout its life. Nurse sharks are long-lived, with an estimated lifespan often cited around 25 years. However, new studies using advanced age estimation methods now suggest some individuals may live for over 40 years, allowing them decades to accumulate their impressive adult size.