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Nature’s Age and Environment Tracker in Fish


Recently, marine biologists at the University of Southampton have developed a technique to decode the chemistry of otoliths.


GS III: Species in News

Otolith Rings: Nature’s Age and Environment Tracker in Fish

Composition and Location:

  • Otoliths, often referred to as “earstones,” are calcified structures found in the ears of bony fishes. They serve as unique indicators of a fish’s age and environmental experiences.

Age Revelation Through Rings:

  • Similar to tree rings, otolith rings disclose the age of a fish. These rings form over time, creating identifiable layers.

Environmental Clues:

  • Isotopes of oxygen within otoliths indicate the temperature a fish encountered during its life. Carbon isotopes offer insights into the conversion speed of food into energy.

Fitness Tracker for Fish:

  • Otoliths act as fitness trackers for fish, providing essential data for their well-being. These stony structures are located behind the fish’s brain.

Types of Otoliths:

  • Sagitta: The largest among the three pairs, sagitta aids in sound detection and the hearing process.
  • Asteriscus: Also involved in sound detection and hearing.
  • Lapillus: This otolith type contributes to sensing gravitational force and sound.

Diversity Among Species:

  • Different fish species exhibit otoliths of distinct shapes and sizes. Cartilaginous fishes like sharks lack otoliths.

Significance in Identification:

  • Otolith features help identify fish species, determine size, age, growth rate, and even the season of death for an individual fish.

Environmental Insights:

  • Analysis of otolith oxygen isotope values provides data on the water temperature where the fish resided.
  • Concentrations of trace elements, such as barium, in otoliths offer clues about the water’s salinity levels.

-Source: The Hindu

February 2024