Amphipods (shrimp-like crustaceans) living at extreme ocean depths possess unique adaptations that have facilitated their evolutionary success within one of Earth’s most unforgiving environments.1-4 This research offers insights into how life can thrive at extreme depths and helps refine our understanding of the physical and chemical limits to which the existence of life is bounded by.
In this study, Western Australian deep-sea amphipods (1,000–6,100 m) were investigated for their organic, inorganic and pollutant chemical profiles. Twenty-one organic metabolites were identified using LC-MS. Additionally, GC-MS enabled the full or partial identification of six more lipids, whose elevated levels likely reflect an adaptation to the deep sea's low food availability. Furthermore, we isolated and identified a novel compound detected only in amphipods beyond a depth of ~4,500 m.
The animal's inorganic chemical profile was evaluated using ICP-MS. Fifty-five elements were screened via solution-phase experiments. A PCA plot was used to visualise the impact of anatomical entity on elemental concentration. This analysis was then applied to five other independent variables, revealing the body part of the organism was the primary factor influencing the variance in elemental composition. Laser ablation mapping uncovered six elements which were consistently enriched in the exoskeleton’s highly calcified layer across all body regions. Subsequent calculations showed strontium undergoes mineralisation through the same pathway as calcium.
Anthropogenic pollutants were also examined. The sole anthropogenic indicator observed was an organic plastic additive believed to be a sampling artefact. The absence of other contaminants indicates that the WA biome remains largely pristine from anthropogenic signatures.