Mystery Object: Can you hear the ocean with this?

Identifying obscure and bizarre objects is all in a day’s work for staff in the Queensland Museum Discovery Centre! Today Dr Jonathan Cramb, Information Officer joins us to share his mystery object of the month.

Can you hear the ocean with this?

Upper surface of the object.

The Mystery

These objects were given to the museum as part of an old teaching collection. They are about 10.5 centimetres long and weigh about 230 grams each. Small cuts on one of the objects show that it has a solid interior.

Apart from a museum, the most likely place that you might find one of these objects would be on the sea floor.

What do you think it might be? A shell from a mollusc? Part of some other type of marine invertebrate? Or perhaps a bone of some kind?

The two specimens are mirror images of each other. Here one shows the upper surface, and the other shows the lower surface.
Close-up of a portion of the upper surface, showing rough texture.

What is it?

These are bones called ‘tympanic bullae’ (part of the middle ear) from a Humpback Whale (Megaptera novaeangliae).

How do we know?

The ear bones of whales are highly distinctive. Each species of mysticete (baleen) whale can be identified just by looking at its ear bones. These bones are very dense, so they are heavier than they look, and are also quite durable.

Why is hearing important for whales?

Animals sense the world around them in different ways. Several of these senses can be impaired when underwater. For example, think of how hard it is to see through muddy water. Sound, however, actually travels faster in the water than in air, so a good sense of hearing is a big advantage in water.

Whales range across oceans when migrating or searching for food. Vocalising (“singing”) allows whales to communicate across vast distances. Low-frequency sounds travel farthest, and the middle ear of whales is adapt to be very sensitive to these sounds. Unfortunately, noise pollution from shipping, sonar and industry has been increasing for several decades now, and this is interfering with whales’ ability to communicate. Some studies indicate that whales are modifying their songs in an effort to be heard about the din.

Humpback Whale, migrating along the Queensland coast.

Uncover more mysteries at the Discovery Centre

Visit the Discovery Centre to see this Mystery of the Month this September. Do you have an interesting question or mystery object? Our helpful and knowledgeable staff can answer your questions through our Ask an Expert inquiry service.