Lytechinus variegatus
Variegated Sea Urchin
A Florida-native algae grazer added to help the Seagrass Meadow push back against redweed shading the shoal grass.
- Common Name
- Variegated Sea Urchin
- Scientific Name
- Lytechinus variegatus
- Realm
- Saltwater
- Biome
- Seagrass Meadow, Marine Shore
- Introduction Method
- Intentional Seeding
- Date First Introduced
- April 26, 2026
- Source / Origin
- Florida field collection, selected for the Seagrass Meadow algae problem.
- Current Estimated Population
- 1 confirmed alive, but condition is concerning.
- Population Status
- Vulnerable
- Carrying Capacity Status
- Unresolved and concerning. One individual remains alive, but repeated shoreline exposure and reduced spine density suggest the current conditions may not be supporting strong long-term health.
- Date Last Observed
- June 10, 2026
Section Notes
Two variegated sea urchins were introduced on April 26, 2026. One individual died shortly after introduction; the other was confirmed alive and feeding on Graceful redweed. By 2026-05-13 and 2026-05-21, the surviving urchin repeatedly returned from the Seagrass Meadow to the Marine Shore shoreline and often positioned itself partially out of the water. On 2026-05-21 it was alive and moving, but spine density appeared reduced, raising concern that it may not be thriving.
- Trophic Level
- Primary Consumer
- Feeding Niche / Method
- Benthic grazer using Aristotle's lantern to scrape and bite algae from surfaces.
- Dietary Inputs
- Confirmed in miniBIOTA: Graceful redweed. General diet: macroalgae, drift algae, seagrass detritus, epiphytes, biofilm, and organic material on benthic surfaces.
- Known Predators
- No predators documented in miniBIOTA.
Section Notes
Confirmed miniBIOTA role is Graceful redweed grazing by the surviving urchin. General literature supports Lytechinus variegatus as a broad macroflora and detrital grazer, but long-term redweed control is still unresolved.
- Temperature Range
- Warm shallow marine water; culture references include roughly 22-28 C, with broader experimental exposure down to 16 C.
- pH Range
- Marine pH range; lab culture documented about 8.2 +/- 0.2. miniBIOTA pH tolerance has not been measured.
- Lighting Requirements
- No direct lighting requirement documented. Its lighting role is indirect: reducing macroalgae shade may help shoal grass receive more light.
- Flow / Aeration Preference
- Needs oxygenated marine water with enough movement to prevent nighttime low-oxygen stress. Repeated shoreline positioning and partial exposure may indicate a condition, resource, or behavioral issue that remains unresolved.
Section Notes
Salinity was matched at introduction, but one urchin died shortly afterward and low nighttime oxygen remains a suspected early stressor. Current tolerance concerns now also include repeated shoreline exposure in the Marine Shore and possible decline in spine condition.
- Expected Lifespan
- Unknown in miniBIOTA.
- Reproductive Strategy
- Separate sexes with broadcast spawning; eggs and sperm are released into the water column, with planktonic larvae before settlement.
- System Reproduction Status
- Not observed
- Growth Rate
- Not documented in miniBIOTA; generally considered a relatively fast-growing sea urchin in research/aquaculture contexts.
Section Notes
No reproduction has been observed in miniBIOTA. With one confirmed survivor and a planktonic larval stage, this should be treated as a grazing trial, not a breeding population.
- Ecological Role
- Macroalgae grazer added to reduce Graceful redweed pressure in the Seagrass Meadow.
- Symbiotic Relationships
- No confirmed symbiotic relationships documented in miniBIOTA.
- Microhabitat Preference
- Originally intended for benthic Seagrass Meadow surfaces and Graceful redweed patches, but the survivor repeatedly returns to the Marine Shore shoreline interface and sometimes positions itself partially out of the water.
Section Notes
Potential food-web correction for redweed overgrowth, but the outcome remains unresolved. Current health concerns mean its useful grazing role may not persist unless the individual stabilizes.
Biomes This Species Lives In
Follow this species across the habitats where it currently appears in the miniBIOTA biosphere.
May 4, 2026
Introduction
Video
Variegated sea urchins introduced to graze Graceful redweed
Variegated sea urchins were added to the Seagrass Meadow after Graceful redweed and other macroalgae continued spreading across the surface and shading the shoal grass below it. During acclimation, one urchin immediately ate a small piece of Graceful redweed, making this the first direct food-web response to the meadow macroalgae problem.
Related Subjects
Seagrass Meadow
Major Impact
Seagrass Meadow food-web intervention: variegated sea urchins added to graze Graceful redweed and other macroalgae shading shoal grass.