Orange-Green Sea Cucumber,  Holothuria (Mertensiothuria) viridiaurantia

Orange-Green Sea Cucumber,  Holothuria (Mertensiothuria) viridiaurantia. Underwater photographs taken in Zihuatanejo Bay, Guerrero, March 2018. Photographs and identificaitons courtesy of Ron Woheau, Zihuatanejo.

Phylogeny:  The Orange-Green Sea Cucumber, Holothuria  (Mertensiothuria) viridiaurantia (Borrero-Pérez & Vanegas-González, 2019), is a member of the Holothuriidae Family of Sea Cucumbers. The Holothuria Genus is one of five genera in the Holothuriidae Family. There are one hundred and sixty species in the Holothuria Genus. The genus name Holothuria comes from the Latinized Greek words meaning “water polyp”. The sub genus Mertensiothuria is named in honor of the German naturalist and physician Karl Heinrich Mertens. The species name viridiaurantia is a combination of the Latin words meaning “green” and “orange colored.”

Morphology: Orange-Green Sea Cucumbers have a round tubular body that is slightly larger at one end, with a tapered head. The oral tentacles are large relative to similar species. Their dorsal surface has a few long, thin, conical, papillae.  The papillae are loosely arranged in four rows. The ventral tube feet are large, thick, and densely distributed.  Orange-Green Sea Cucumbers have an olive-green background and white-orange papillae, tube feet, and tentacles.  They reach a maximum of 7.0 cm (2.7 inches) in length. Some sources extend this length to 10 cm or 13 cm, but these may have been confused with the similar looking  Tiger-tail Sea Cucember, Holothuria (Mertensiothuria) hilla, which has a cosmopolitan distribution, but is more prevalent in the Indo-Pacific.

Habitat and Distribution: Due  to it’s recent introduction the Orange-Green Sea Cucumbers has been poortly studied with limited information published related to it’s  geographic range. They are generally associated with rocky bottoms, but may be found on mud or sand substrates, under or around rocks. They are found as depths from the intertidal zone to, at least, 15 m (49 feet). They are a Tropical Eastern Pacific species with a very limited range in Mexican waters of the Pacific Ocean being found from Compostela, Nayarit to Guatemala.

Diet:  Orange-Green Sea Cucumbers are a poorly studied and understood species. There is very limited documentation of their diet. Other sea cucumbers in Holothuria Genus are detritivores ingesting sea floor sediment and digesting the organic matter, such as microalgae and detritus expeling sand and other non-digestible matter.

Predators:  The predation of Orange-Green Sea Cucumbers is poorly documented. Other sea cucumbers in Holothuria Genus are preyed upon by anemones, shore birds, crabs, fish, gastropods, octopuses, and sea stars.

Reproduction:  Orange-Green Sea Cucumbers are gonochoric (male or female for life). They reproduce sexually through broadcast spawning, with external fertilization. The gametes form planktonic larvae.  After several weeks the larvae settle to the bottom to begin their benthic life.

Ecosystem Interactions: Orange-Green Sea Cucumbers involvement in any types of  commensal, parasitic or symbiotic relationships has not been documented. Similar sea cucumbers host parasitic bacteria, metazoa and protozoa.

Human Interactions: Orange-Green Sea Cucumbers have no direct impact on human activities. From a conservation perspective the Orange-Green Sea Cucumber has not been formally evaluated.

Synonyms: None