The endless expanse of the ocean’s midnight zone offers plenty of room to stretch out. Here, some animals can grow to great lengths. Siphonophores are gelatinous animals composed of specialized parts growing together in a chain. The woolly siphonophore (Apolemia lanosa) is a shaggy species we often encounter in Monterey Bay. We know they can reach at least five meters (16 feet) in length, but other siphonophores can be as long as a blue whale! We often encounter the woolly siphonophore in a spiral coil dangling a curtain of tentacles. Specialized stinging cells stun any unfortunate animal that blunders into those sprawling tentacles. The woolly siphonophore is one of two new Apolemia species we discovered in Monterey Bay. Our team has worked with collaborators around the world to describe 11 previously unknown siphonophore species off the California coast. Understanding and documenting deep-sea biodiversity is increasingly critical. Fishing pressure, pollution, and climate change all threaten the deep ocean. We urgently need to establish a baseline of what lives in the deep sea to monitor ongoing human impacts on this environment. Learn more about this and other fascinating animals of the deep: https://mbari.co/WoollySiphonophore Script writer: Kristine Walz Science advisor: Steve Haddock Editor: Ted Blanco Narrator: Madeline Go Motion Graphics: Madeline Go Production team: Heidi Cullen, Madeline Go, Larissa Lemon, Raúl Nava, Kyra Schlining, Nancy Jacobsen Stout, Susan von Thun, Kristine Walz Music: 'Beautiful Spa Music' by Gusto from Storyblocks.com References: Choy, C.A., S.H.D. Haddock, and B.H. Robison (2017). Deep pelagic food web structure as revealed by in situ feeding observations. Proceedings of the Royal Society B, 284: 20172116. doi.org/10.1098/rspb.2017.2116 Damian-Serrano, A., S.H.D. Haddock, and C.W. Dunn (2021). The evolution of siphonophore tentilla for specialized prey capture in the open ocean. Proceedings of the National Academy of Sciences, 118(8): e2005063118. doi.org/10.1073/pnas.2005063118 Damian-Serrano, A., E.D. Hetherington, C.A. Choy, S.H.D. Haddock, A. Lapides, and C.W. Dunn (2022). Characterizing the secret diets of siphonophores (Cnidaria: Hydrozoa) using DNA metabarcoding. PLoS ONE, 17(5): e0267761. doi.org/10.1371/journal.pone.0267761 Gasca, R. and S.H.D. Haddock (2016). The rare deep-living hyperiid amphipod Megalanceoloides remipes (Barnard, 1932): complementary description and symbiosis. Zootaxa, 4178 (1): 138-144. doi.org/10.11646/zootaxa.4178.1.7 Gasca, R., R. Hoover, and S.H.D. Haddock (2015). New symbiotic associations of hyperiid amphipods (Peracarida) with gelatinous zooplankton in deep waters off California. Journal of the Marine Biological Association of the United Kingdom, 95(3): 503-511. doi.org/10.1017/S0025315414001416 ​​Haddock, S.H.D. and J.F. Case (1999). Bioluminescence spectra of shallow and deep-sea gelatinous zooplankton: Ctenophores, medusae and siphonophores. Marine Biology, 133: 571-582. doi.org/10.1007/s002270050497 Hetherington, E.D., A. Damian-Serrano, S.H.D. Haddock, C.W. Dunn, and C.A. Choy (2022). Integrating siphonophores into marine food-web ecology. Limnology and Oceanography Letters, 7: 81-95. doi.org/10.1002/lol2.10235 Siebert, S., P.R. Pugh, S.H.D. Haddock, and C.W. Dunn (2013). Re-evaluation of characters in Apolemiidae (Siphonophora), with description of two new species from Monterey Bay, California. Zootaxa, 3702 (3): 201-232. doi.org/10.11646/zootaxa.3702.3.1