muscles need iron
so do mussels it appears
such sticky anchors
Iron is an essential element for almost all living organisms. The majority of iron in mammals is found in red blood cells (haemoglobin) and muscle cells (myoglobin), supporting the transport, storage and release of oxygen. In humans, iron deficiency is the most common nutritional deficiency in the world and can lead to iron-deficiency anaemia, symptoms of which include fatigue, headaches, weakness, angina, breathlessness, complications during pregnancy and delayed growth in infants and children.
Iron is also important for many animals, utilised to help strengthen hard materials such as rodent teeth or the carbonate armour of some gastropods. Yet iron can be found in soft biological materials too, including the sticky anchors that mussels use to attach to rocks and the threads that connect those adhesives to the mussels’ inner tissues.
To investigate the importance of iron in mussel anchors, Hamada et al. (2020) varied seawater iron levels in a controlled environment and examined adhesive thread samples from Blue mussels (Mytilus edulis) which had been living in the water for 3 days. The researchers measured thread strength by securing the entire length of the threads and measuring how much force was required to pull them until the adhesive failed.
Adhesive strength increased as the iron level of the water increased until an optimal amount was reached, after which the adhesive strength declined. Examination of the plaques themselves also revealed differences in morphology, including colour and microstructural features, arising from the different iron levels of the water.
The results confirm that iron is a key component of how mussels anchor themselves to rocks and demonstrate how changing ocean chemistry might affect these molluscs in the future.
Further reading: https://doi.org/10.1021/acs.est.0c02392