Intertidal organisms, including nemerteans, may be subject to widely varying temperatures, including daily tidal-related fluctuations and seasonal changes.  High temperatures experienced daily or seasonally may damage protein. Proteins damaged by heat and other agents are “chaparoned” and mended by special heat-shock proteins (HSPs¹).  The presence of HSPs in nemerteans has been confirmed for Paranemertes peregrina collected from mudflats at Bodega Bay, California.  After determining that 36^oC is lethal to the worms, the authors expose worms to temperatures of 34^oC² for 2h, let them recover in ambient seawater of 15^oC for 2h, and monitor their tissues and the tissues of control worms for presence of HSP 70³.  Although the effect is relatively small, perhaps owing mostly to the presence of a large residual content of HSP 70 in the tissues of control worms, it is statistically significant (see histogram).  The authors suggest that the high HSP levels in the control worms may owe to an especially long tidal-exposure (5-6h) on the day of collection in August, when mud and tidepool temperatures were high.  The authors note that, to the best of their knowledge, this is the first report of HSPs in the phylum Nemertea.  Okasaki et al. 2001 Hydrobiologia 456: 211. Photograph courtesy Rebecca Kordas, Biodiversity Research Centre, University of British Columbia, Vancouver.

NOTE¹  HSPs are nearly ubiquitous in intertidal marine invertebrates, and have been identified in many species of cnidarians, molluscs, and crustaceans.  Further information on HSPs in west-coast intertidal invertebrates can be found in the ODYSSEY at:  LEARN ABOUT ABALONES & RELATIVES: HEAT-SHOCK PROTEINS, LEARN ABOUT MUSSELS: LIFE IN THE INTERTIDAL ZONE: HEAT-SHOCK PROTEINS, and LEARN ABOUT LIMPETS: LIFE IN THE INTERTIDAL ZONE: TEMPERATURE STRESS

NOTE² the authors note that not all worms survive this temperature, and those that do exhibit stress behaviours such as proboscis eversion, mucus secretion, and sluggish movement.  The authors suggest that future experiments on this species and perhaps others should be done at lower stress temperatures and include a longer recovery time

NOTE³ HSPs are categorised by their molecular mass.  There are many different kinds, with HSP 70 being one of the more common types

Paranemertes peregrina withdrawing
its proboscis following an unsuccessful
attack on a nereid worm 1X