Creature Feature: Red Siphonophore

This spectacular siphonophore is a sight to see.

By Monterey Bay Aquarium Research Institute

Weird and Wonderful: This spectacular deep-sea siphonophore is a sight to see by Monterey Bay Aquarium Research Institute (MBARI)Monterey Bay Aquarium Research Institute

We’ve discovered a rainbow of siphonophores in the depths of Monterey Bay and beyond, like this stunningly scarlet species described by MBARI researchers and their collaborators in 2005.

Red siphonophore, Marrus claudanielis (2002) by MBARIMonterey Bay Aquarium Research Institute

Siphonophores (pronounced “sigh-fawn-oh-fours”) are colonial creatures made up of specialized segments that work together as one. Scientists have described some 175 siphonophore species. Most follow a similar body plan—a gas-filled float provides buoyancy, swimming bells propel the colony, and a central stem bears specialized parts for feeding, defense, and reproduction. Most siphonophores live far from the seafloor and call the endless expanse of the ocean’s midwater zone their home.  

Red siphonophore, Marrus claudanielis (2003) by MBARIMonterey Bay Aquarium Research Institute

Because their delicate bodies can break apart at the slightest touch, siphonophores are hard to study. Thankfully, MBARI’s remotely operated vehicles (ROVs) give scientists the opportunity to get a close-up look at deep-sea siphonophores without damaging them. Our skilled pilots carefully maneuver the ROV to record stunning video of these delicate drifters. These observations complement specimens we gingerly collect with samplers on the ROV.

Red siphonophore, Marrus claudanielis (2018) by MBARIMonterey Bay Aquarium Research Institute

MBARI researchers and collaborators described the red siphonophore (Marrus claudanielis) in 2005 from specimens collected by ROVs off California and New Jersey. With observations off both coasts of North America, this species is likely widely distributed, but has simply eluded scientists in the past. Although the deep sea is the largest environment on Earth, we’ve only explored a miniscule fraction of these midnight waters. Who knows what other fascinating discoveries linger in the darkness waiting to be found?

Red siphonophore, Marrus claudanielis (2017) by MBARIMonterey Bay Aquarium Research Institute

The red siphonophore’s name recognizes its striking scarlet coloration, but its scientific name—Marrus claudanielis—honors the husband-and-wife team Claude and Danièle Carré for their contributions to our understanding of siphonophore biology.

Red siphonophore, Marrus claudanielis (2019) by MBARIMonterey Bay Aquarium Research Institute

The red siphonophore (Marrus claudanielis) lives in the midwater—the vast expanse of open water 200 meters (660 feet) below the surface and 200 meters above the seafloor—and never comes in contact with hard surfaces. Like other siphonophores, it’s hard to collect and study in the lab, but even observations in the field prove tricky for MBARI scientists. This species is sensitive to light and if we’re not careful, the lights on the ROV cause the siphonophore to shed its body parts.

Detritus sampler collecting a red siphonophore, Marrus claudanielis (2015) by MBARIMonterey Bay Aquarium Research Institute

Video captured by MBARI’s ROVs is critical to building our understanding of deep-sea siphonophores, but we also need to collect samples to formally describe a new species. We use a detritus sampler to carefully collect a specimen for closer examination in the lab to document its anatomy and genetics. 

Orange lantern siphonophore, Marrus orthocanna (2009) by MBARIMonterey Bay Aquarium Research Institute

While exploring the depths of Astoria Canyon off the coast of Oregon in 2009, MBARI’s ROV Doc Ricketts spotted the orange lantern siphonophore (Marrus orthocanna), a close cousin of the red siphonophore (Marrus claudanielis). While the two species look similar in appearance, the orange lantern siphonophore is typically more orange in color, has hook-shaped canals along its length, and grows longer than the red siphonophore.

Red siphonophore, Marrus claudanielis (2015) by MBARIMonterey Bay Aquarium Research Institute

MBARI’s ROVs are shedding new light on the residents of the midwater, including those that live in the midnight zone—the inky depths below 1,000 meters (3,300 feet) that scientists call the bathypelagic zone. This red siphonophore (Marrus claudanielis) was observed by MBARI’s ROV Doc Ricketts at a depth of approximately 1,500 meters (4,900 feet).

There's no such thing as a jellyfish (2011-05-31) by Monterey Bay Aquarium Research Institute (MBARI)Monterey Bay Aquarium Research Institute

The ocean is home to a variety of jelly-like animals. Siphonophores are close cousins of jellies and exhibit a unique colonial body plan that distributes individual tasks—like feeding, movement, and reproduction—among specialized regions along the length of the animal. Siphonophores are abundant predators in the deep sea.

Red siphonophore, Marrus claudanielis (2006) by MBARIMonterey Bay Aquarium Research Institute

Scientists classify siphonophores into three groups—physonect siphonophores have swimming bells and a gas-filled float; cystonect siphonophores have a float, but no swimming bells; and calycophoran siphonophores have swimming bells, but no float. The red  (Marrus claudanielis) is a physonect siphonophore. 

Pneumatophore of a red siphonophore, Marrus claudanielis (2006) by MBARIMonterey Bay Aquarium Research Institute

A small, gas-filled float called a pneumatophore provides buoyancy for a red siphonophore (Marrus claudanielis).

Nectophores of a red siphonophore, Marrus claudanielis (2006) by MBARIMonterey Bay Aquarium Research Institute

Just behind the gas-filled pneumatophore are swimming bells called nectophores. Just like the muscular bell of a jelly, these expand and contract to propel a red siphonophore (Marrus claudanielis) through the water. When threatened, the red siphonophore can jettison its swimming bells, which glow with bioluminescence to confuse predators while the siphonophore makes its escape.  

Siphosome of a red siphonophore, Marrus claudanielis (2006) by MBARIMonterey Bay Aquarium Research Institute

A central stem called a siphosome runs the length of a red siphonophore (Marrus claudanielis) and connects each individual in the colony to one another. Feeding polyps (gastrozooids) extend fine tentacles to capture food. Frilly bracts are loaded with stinging cells to defend the siphonophore from predators. Clusters of gonophores aid in spawning and reproduction.

With specialized parts for swimming, feeding, digestion, and reproduction, the body plan of a siphonophore is vastly different from our own. However, just like us, siphonophores start from an embryo and grow larger with age. As they grow, they bud new parts in repeated sequences.

Red siphonophore, Marrus claudanielis by MBARIMonterey Bay Aquarium Research Institute

Fast Facts

Range: known from northeastern Pacific Ocean and northwestern Atlantic Ocean, but may be more widespread
Depth: 500 to 1,500 meters (1,600 to 4,900 feet)
Size: 30 centimeters (12 inches)
Diet: unknown, but likely crustaceans and possibly small fishes

Red siphonophore, Marrus claudanielis (2003) by MBARIMonterey Bay Aquarium Research Institute

Research publications

Dunn, C.W., P.R. Pugh, and S.H.D. Haddock (2005). Marrus claudanielis, a new species of deep-sea physonect siphonophore (Siphonophora, Physonectae). Bulletin of Marine Science, 76: 699-714.

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The mission of MBARI is to advance marine science and technology to understand a changing ocean. To learn more, visit mbari.org and follow MBARI on Facebook, Instagram, LinkedIn, Tumblr, Twitter, and YouTube.

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