Britannica
Sources used in this answer
Why were shallow warm-water marine invertebrates especially vulnerable during the Permian extinction?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Permian extinction
The diversity of marine animal families since late Precambrian time. The data for the curve comprise only those families that are reliably preserved in the fossil record; the 1,900 value for living families also includes those families rarely preserved as fossils. The several pronounced dips in the curve correspond to major mass-extinction events. The most catastrophic extinction took place at the end of the Permian Period.
Shallow warm-water marine invertebrates were particularly vulnerable during the Permian extinction primarily due to severe temperature crises in ocean surface waters.12
Research suggests that water temperatures rose significantly, reaching levels that were likely too warm for many species to survive. Hypotheses regarding this vulnerability include:12
- Thermal Intolerance: Water temperatures exceeding 24–28 °C (about 75–82 °F) may have exceeded the physiological limits of many invertebrates, leaving only those specialized for high-temperature environments, such as shallow lagoons, to survive.12
- Loss of Symbionts: Some marine invertebrates relied on photosynthetic symbionts living within their tissues. It is hypothesized that these symbionts could not withstand the rising ocean temperatures and abandoned their hosts, depriving the invertebrates of a critical biological resource.12
These temperature spikes, which may have increased seawater temperatures to as high as 30–32 °C (about 86–90 °F) near the Permian-Triassic boundary, contributed to the protracted and catastrophic losses observed in groups such as trilobites, corals, and echinoderms.132