Discovering bones on a beach often sparks curiosity about their origin. While most finds are animal remains, understanding how to assess them is important for personal safety and environmental awareness. Knowing bone characteristics helps distinguish possibilities and guides appropriate, respectful handling.
Initial Assessment: Is It a Bone and Is It Human?
When encountering a bone-like object on the beach, examine it closely to determine if it’s biological material, not rock, wood, or shell. Real bones have a porous texture and, if broken, reveal internal canals and a webbed pattern, distinct from a solid interior. Bones also possess a specific weight relative to their size.
If the object appears to be a bone, assess whether it might be human. This distinction relies on differences in size, shape, and density. Human bones are generally less dense and more porous than many animal bones. For instance, the outer layer of a human femur or humerus is about one-quarter of its total diameter, compared to roughly half in many animal limb bones.
Specific anatomical features also provide clues. A human skull, for instance, has a large, bulbous cranial vault and a relatively small face, with the chin typically present. In contrast, many animals possess smaller braincases and larger facial structures. Human long bones like the tibia and fibula in the lower leg are typically separate, while in many animals, these bones may be fused. The human pelvis, adapted for upright walking, is broad and bowl-shaped, differing from the longer, more blade-like pelvises found in most animals.
Key Features for Animal Bone Identification
Once a bone is identified as non-human, several features can help determine the type of animal it came from. Size and overall shape are fundamental indicators; a large, robust bone suggests a larger animal, while smaller, more delicate bones point to smaller creatures. The specific form of the bone, whether a long limb bone, a flat skull plate, or a vertebra, can also narrow down possibilities.
Bone density and weight vary among species, providing additional information. Marine mammal bones, for example, often possess a dense, robust structure. The presence or absence of a marrow cavity and the thickness of bone walls offer insights into an animal’s physiology. Birds, for instance, typically have hollow, lightweight bones adapted for flight.
Joint surfaces, or articulation points, are highly specific to an animal’s locomotion and can be very telling. These surfaces show how bones connected, indicating whether the animal was built for running, swimming, or flying. The texture of the bone surface—smooth, porous, or rough with muscle markings—also provides clues about the animal’s size and the development of its musculature. Color variations can reflect natural pigmentation or staining from the marine environment.
Common Bone Finds on Beaches
Beaches are dynamic environments where various animal bones can wash ashore, often originating from both marine and terrestrial sources. Marine mammals frequently contribute large, dense bones to beach finds. Whale vertebrae, for example, can be notably large, sometimes resembling the size and shape of a dinner plate. Flipper bones from seals or other marine mammals might appear short, powerful, and flattened, reflecting adaptations for swimming.
Fish bones are also common, though they are often smaller and more delicate than mammal bones. Fish vertebrae can have distinct shapes, and some species exhibit hyperostosis, a condition where certain bones become unusually swollen or dense. These unique characteristics can sometimes make fish bones appear unusual to the untrained eye.
Bird bones are frequently found and are typically identifiable by their lightweight, often hollow structure, which is an adaptation for flight. Sternums (breastbones) from seabirds, such as ducks or geese, are common finds and can be recognized by their distinct keeled shape. While less frequent, bones from land animals, such as deer or livestock, can also wash onto beaches, carried by rivers or tides. These bones generally differ from marine species in their structure and density, often appearing longer and thinner in limb bones compared to the robust bones of marine mammals.
What to Do After Finding a Bone
If a bone found on the beach appears to be human, it is important to avoid touching or disturbing it. Immediately mark the location without altering the scene, and if possible, take photographs from various angles to document the find. The next step is to promptly contact local law enforcement, such as the police non-emergency line, or the medical examiner’s office. Preserving the scene is important for forensic analysis, as disturbing the remains could compromise potential investigations.
When a bone is clearly identified as animal, the course of action depends on local regulations and the species involved. Collecting animal remains from beaches can be subject to specific laws, particularly concerning protected species. If the bone is from a common animal and collection is permitted, it can be cleaned and preserved. However, if there is any doubt about the species or legality, or if the bone is large and appears to be from a protected animal, it is advisable to leave it in place. This approach helps ensure compliance with regulations and respects wildlife.