The round purple object on this bubblegum coral is in fact a dumbo octopus egg. It was seen while exploring at a depth of ~1,630 meters (~5,350 feet) at the seamount dubbed “Kahalewai”. We saw a similar egg on the Discovering the Deep: Exploring Remote Pacific Marine Protected Areas expedition.

The round purple object on this bubblegum coral is a dumbo octopus egg. It was seen while exploring at a depth of ~1,630 meters (~5,350 feet) at the seamount dubbed "Kahalewai." We saw a similar egg on the Discovering the Deep: Exploring Remote Pacific Marine Protected Areas expedition. Image courtesy of the NOAA Office of Ocean Exploration and Research, Mountains in the Deep: Exploring the Central Pacific Basin. Download larger version (jpg, 1.1 MB).

This giant bamboo coral was seen at close to  ~1,700 meters (~5580 feet) of depth on the seamount dubbed “Kahalewai”. It was about as big as ROV Deep Discoverer. We took a small sample of this coral to learn more about it.

This giant bamboo coral was seen at close to ~1,700 meters (~5,580 feet) depth on the seamount dubbed "Kahalewai." It was about as big as ROV Deep Discoverer. We took a small sample of this coral to learn more about it. Image courtesy of the NOAA Office of Ocean Exploration and Research, Mountains in the Deep: Exploring the Central Pacific Basin. Download larger version (jpg, 2.8 MB).

Dive 04: "Kahalewai"
May 4, 2017
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Dive 04: Big Yellow Coral

This giant bamboo coral was seen during Dive 04, at close to ~1,700 meters (~5,580 feet) depth on a seamount dubbed "Kahalewai." The coral was almost as big as removely operated vehicle Deep Discoverer, making scientists speculate that the coral colony is likely hundreds of years old. Video courtesy of the NOAA Office of Ocean Exploration and Research, Mountains in the Deep: Exploring the Central Pacific Basin. Download (mp4, 22.7 MB)

We had a great dive at a previously unmapped seamount dubbed "Kahalewai." The dive targeted the prominent southern ridge of the seamount at depths between ~1,700 and 1,500 meters (5,580 and 4,920 feet) depth. We saw a variety of midwater animals during the descent, as well as near the seafloor during the dive. These included siphonophores (colonial jellyfish), sergestid shrimp, jellyfish, a Bostigrinus (a carnivorous doliolid or tunicate), pelagothurians (pelagic sea cucumbers), and a squid.

When we reached the bottom, we were treated to a view of a colorful overhang that was populated by low-growing octocorals, encrusting blue sponge, and both gooseneck and acorn barnacles. The ridge feature had pockets of high-density communities that included corals and sponges and barnacles. We observed a number of corals, including an immense yellow colony, a few Iridogorgia, chrysogorgiids, and bubblegum coral. Only a couple of species of fish were recorded: an eel and small elongate rattail. The dominant fauna were crinoids, both feather stars and stalked sea lilies. Many of the stalked crinoids were home to numerous polychaetes, specialized predators of crinoids. Sea pens were abundant in rippled sediment channels set among the exposed rock. Sea urchins were also common and abundant throughout the dive, mainly species with long, curved spines or robust thick spines, but we also saw two species of leather urchins. Other interesting observations included numerous hermit crabs; a chiton leaving feeding traces on rock surfaces; and an aplacophoran, a specialized worm-like mollusc that was feeding on a bamboo coral.

Throughout the dive, a thick ferro-manganese (Fe-Mn) crust was evident, indicating the underlying rock is relatively old. Light-colored sediments were deposited in crevasses and low areas. In some of the larger areas of sediment cover, we observed high densities of sea pens. Ripples in the sediment indicated a dominant flow direction from north to south, consistent with the bottom current conditions reported by the remotely operated vehicle (ROV) pilots. Despite the Fe-Mn crust covering the rock, the ROV imaged collapsed lava tubes and primary volcanic flow (lobate to pillow) structures in some places.