Ruby seadragon (Phyllopteryx dewysea)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Syngnathiformes · Family: Syngnathidae · Genus: Phyllopteryx.

Accepted name: Phyllopteryx dewysea · Authority: Stiller, Wilson & Rouse, 2015 · Taxonomic status: accepted · AphiaID: 834213.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=834213 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

Measured values published by FishBase for Phyllopteryx dewysea. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 25.899999618530273 cm · Depth range: 50–72 m · Habitat zone: reef-associated · Body shape: other · Vulnerability index: 15.9 of 100 · Fishery importance: bycatch · Aquarium trade: never/rarely.

FishBase notes: Occurs more offshore in slightly deeper waters; at 50+m with complex habitat of a mixed reef and sandy habitat with two paratypes collected from the continental shelf (Ref. 100032).

Source: FishBase species summary (SpecCode 68465) — https://www.fishbase.se/summary/Phyllopteryx-dewysea.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Phyllopteryx dewysea Stiller, Wilson & Rouse, 2015 as Data Deficient (code DD). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 87568739) — https://www.iucnredlist.org/species/87568739/0; GBIF IUCN Red List category endpoint (taxonKey 7443835) — https://api.gbif.org/v1/species/7443835/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

The ruby seadragon is named to honor Mary 'Dewy' Lowe, a supporter of seadragon conservation and research.

The ruby seadragon is characterized by a ruby red body with pink vertical bars that extend halfway up, meeting lateral trunk ridges. They have a slender, elongated body, like the common seadragon. Their body has 18 trunk segments with an enlarged pectoral area and spines. In contrast to the other two seadragon species, the ruby seadragon has a curved prehensile tail with a yellow tip. It also lacks dermal appendages (the leaf-like structures on other seadragon species) despite possessing the bony spines that these would attach to.

It is possible that ruby seadragons exhibit sexual dimorphism. Of the two live ruby seadragon observations, one was potentially a female. This female had a deeper, circular body shape, with darker red coloration and obvious vertical bars.

The holotype (a single individual used to formally describe the species) of the ruby seadragon was a male carrying its brood. In addition to the above description, it had light snout markings; when preserved, its uniform coloration faded to brown. Five paratypes (additional specimen representing species variation) were identified following the discovery of the holotype. The holotype specimen is kept in the Western Australian Museum in Perth (Code WAM P33223.002).

There is no difference in quantitative measurements between the three seadragon species, but the ruby seadragon can be distinguished through visual observation. The common seadragon has a spotted appearance that remains after preservation and the leafy seadragon has white and purple vertical bars that extend past the body. Furthermore, the common and leafy seadragons have paired backwards-facing spines and a head spine. These differences are in addition to the aforementioned.

As of 2025, there are no estimates of ruby seadragon population sizes.

As of 2017, all of the 6 ruby seadragon specimens were collected in Western Australia. Three of the specimens were near Perth, one was in the Recherche Archipelago, one at Culver Cliffs, and the last near Esperance. It is likely that the ruby seadragon evaded prior identification because of their deep-water range, outside of the recreational scuba depth. The holotype was trawled in the Recherche Archipelago at a depth of 51–72 meters, indicating that ruby seadragon species may prefer deeper waters. This theory was confirmed in April 2016 during a survey of the Recherche Archipelago (at 50+ meters), resulting in the first live records of the ruby seadragon; these two sightings, in addition to the previous male with brood (2007), suggest a viable population in the Recherche Archipelago. Prior specimen locations may indicate a wider range in Western Australia, but this claim requires further evidence.

The Recherche Archipelago is the potential locality of the ruby seadragon. This area of Western Australia is a 230-kilometer chain of approximately 105 islands and 1500 islets. As of 2005, there was little research into the ocean currents of the area, but the region is described as storm-dominated with few periods of calm. Three habitat types have been identified (seagrass, reef, and sand) and split into eight categories of seabed: dense, medium, sparse, and patchy seagrass; flat platform, heavy limestone, and granite reef; and bare sand. Species sampling revealed different fish communities between these broad habitat types, influenced by changes in vegetation density. There is also a wide variety of soft bottom substrate throughout the Recherche Archipelago region. Overall, the habitat of the ruby seadragon is likely a complex mix of reef and sand at 50+ meter depth. During the 2016 Recherche Archipelago survey, the habitat was described as soft sand substrate layered over hard reef with a bottom temperature of 18 °Celsius. The community composition included large demosponges, gorgonians, foliose bryozoan colonies, among others.

The proposed habitat of the ruby seadragon is dramatically different from that of the common and leafy seadragons. The common and leafy seadragons are found in a range of depths (1-50 meters and 20+ meters, respectively), from shallow estuaries to deep offshore reefs. They feed on small crustaceans along kelp reefs and sandy edges. This contrasts the open, turbulent, deep habitat of the ruby seadragon, characterized by soft sand and hard reef mix.

Due to limited knowledge, researchers are uncertain about the behavior, ecology, and life cycle of the ruby seadragon, and of other seadragon species. The assumptions below are subject to change as further research is conducted.

The holotype of the ruby seadragon was collected with brood, so the reproductive strategy of this species resembles other seadragons. In the common and leafy seadragon species, the female's eggs are transferred to the male's brood patch for incubation until the young hatch.

The ruby seadragon diet is not known but its snout morphology suggests that it is adapted for predation, like other seadragon species. The common and leafy seadragons prey on small crustaceans and mysids. In observation, the ruby seadragons were seen striking at sandy substrate, potentially feeding on similar prey.

An interesting trait of the ruby seadragon is the lack of dermal appendages despite possessing bony spines for these structures. This is attributed to the sparse and turbulent habitat they are sighted in, as bulky appendages can add drag and resistance during strong surges. They would not serve the same camouflaging purpose as for the common and leafy seadragons. The red coloration of the ruby seadragon may be a camouflage strategy in the low-light depths that this species prefers. Depth has a substantial effect on the crypticity of a species, dorsal coloration of species trends to red with increasing depth. In low-light environments, red coloration is considered a defense against bioluminescence, particularly at 400+ meter depths. This is because the spectrum of bioluminescence lacks red wavelengths, therefore red surfaces are not visible to species that rely on bioluminescence.

Source: Wikipedia: Ruby seadragon — https://en.wikipedia.org/wiki/Ruby_seadragon (CC BY-SA 4.0). Accessed 2026-09-23.