Flower Sea Urchin, Toxopneustes roseus
Flower Sea Urchin, Toxopneustes roseus. Urchin collected at Km 17, El Tule, Baja California Sur, February 2011. Size: 8.0 cm (3.15 inches).
Flower Sea Urchin, Toxopneustes roseus. Underwater photograph taken in Zihuatanejo Bay, Guerrero, March 2018. Photograph courtesy of Maude Jette, Dive Zihuantanejo, www.Divezihuantanejo.com.
Flower Sea Urchin, Toxopneustes roseus. Underwater photograph taken in Zihuatanejo Bay, Guerrero, February 2022. Photograph and identification courtesy of Ron Woheau, Zihuatanejo.
Flower Sea Urchin, Toxopneustes roseus. Urchin collected off the beach at Agua Verde, Baja California Sur, February 2019. Size: 9.5 cm (3.75 inches) x 3.8 cm (1.5 inches). Collection and photographs courtesy of Barry Mastro, Escondido, California.
Phylogeny: The Flower Sea Urchin, Toxopneustes roseus (A. Agassiz, 1863), is a member of the Toxopneustidae Family of Sea Urchins. The Toxopneustidae Family contains eleven genera and around thirty-five species. The genus name Toxopneustes comes from the Greek words meaning “poison breath”. This refers to these urchins having venomous pedicellariae. This species is also known as the Collector Urchin, Pink Flower Urchin, and Rose Flower Urchin. In Mexico they are called Erizo Florado and Erizo Merino Florcada.
Morphology: Flower Sea Urchins have a rigid globular test with pentaradial symmetry. The test is covered in distinctive petal shaped pedicellariae (pink, yellow, or white in color with a central purple dot) and very short spines that are often hidden behind the pedicellariae. There are four types of pedicellariae that each possess a specific form and function. The ophicephalous pedicellariae resemble tube feet and are responsible for keeping the outside of the organism clean of algae, encrusting organisms, and other unwanted debris. These pedicellariae, which give rise to their common name, are often held open giving this urchin the appearance of being covered with flowers. The common name “collector urchin” comes from the fact that the majority of these urchins found in the wild are covered with algae, shells, and other debris from their surroundings. It is believed that either they use this debris as a ballast to prevent being swept away by wave surges, or as sun protection. They are a uniform pink, purple or red in color. Flower Sea Urchins reach a maximum of 12 cm (4.7 inches) in diameter.
Habitat and Distribution: The Flower Sea Urchin is found in algae beds, coral reefs, rocky environments, sand and mud substrates. They live in the lower intertidal zone, and to depths up to 24 m (80 feet). The Flower Sea Urchin is a subtropical to tropical Eastern Pacific species. In Mexican waters they range from Guerrero Negro (Bahia Tortugas), Baja California, to Guatemala.
Diet: Flower Sea Urchins are grazers that feed primarily on coralline algae.
Predation: there is limited documentation of predation regarding Flower Sea Urchins. It is thought that they may be prey for fish, gastropods and sea stars, especially in their juvenile form. They utilize toxic venom for defense that is found within their globiferous pedicellariae, each of which have a head with three moveable jaws. Each jaw has a sharp tooth with a venom sack at its base. This deters many would-be predators.
Reproduction: Flower Sea Urchins are gonochoric (male or female for life). They reproduce sexually through broadcast spawning with external fertilization. The fertilized eggs hatch into planktonic larvae and, after several months, sink to the bottom to metamorphose into juvenile urchins. Flower Sea Urchins shed their covering items before spawning.
Ecosystem Interactions: Flower Sea Urchins act as a population controller of rhodolith (coralline algae) beds and they act to turn over soft substrates, which redistributes oxygen, nutrients, and species distribution. Their involvement in any parasitic, commensal, or mutualistic relationships has not been documented.
Human Interactions: Flower Sea Urchins have a limited impact on human activities. They are venomous and can deliver painful stings if touched. There are anecdotal accounts of facial paralysis and respiratory difficulty resulting from being stung in the hand by urchins in this genus. From a conservation perspective Flower Sea Urchins have not been evaluated, however they are common with a wide distribution and should be considered to be of Least Concern.
Synonyms: Boletia picta, Boletia roseus, and Lytechinus roseus.