An unusually large crayfish found in Kentucky led Caitlin Bloomer to investigate North America's biggest examples. She thought her catch might be the largest ever recorded, but a colleague said he had caught bigger ones. Bloomer then contacted biologists and museum staff across the country. The search identified 20 particularly large crayfish from 18 species. Her own catch earned a place on the list.
The largest was a Tennessee bottlebrush crayfish held at West Liberty University in West Virginia. Its main body measured 86.6 millimetres, excluding the tail, claws and feelers. Researchers noticed that the biggest individuals generally reached around 80 millimetres in this body measurement, although some crayfish elsewhere in the world grow much larger.
The team looked for connections between maximum size and geographical location, oxygen levels or habitat, meaning the environment where an animal lives. None showed a clear relationship. Instead, the researchers suggested that the animals' hard outer shells or muscle structure might restrict growth. This remains a possible explanation rather than a proven answer, and further research is needed.
