Brachidontes exustus
Found on hard surfaces in the Seagrass Meadow, this small ribbed bivalve filters suspended phytoplankton and fine particles from the water column, persisting as a filter feeder after eastern oysters failed in the same biome.
The Scorched Mussel (Brachidontes exustus) is a small ribbed bivalve filter feeder present in the miniBIOTA Seagrass Meadow. A founding population was in the system before February 2026 and persisted after the eastern oyster population failed; by February 20, 2026, three individuals were confirmed, noted as more persistent than expected. On April 22, 2026, three additional wild-collected individuals from a brackish tidal ditch in Spring Hill, FL were drip-acclimated to marine salinity and introduced to the Seagrass Meadow. No feeding, reproduction, or post-April population count has been confirmed. Population status is Uncertain.
Brachidontes exustus is distributed from the Gulf of Mexico and Caribbean coast northward along the Atlantic seaboard to North Carolina. It is among the most abundant small mussels on Florida's rocky, shell, and hard-substrate intertidal shorelines, mangrove roots, seawalls, and marina pilings. It commonly occurs in brackish to full marine water, making it highly relevant to Florida's coastal habitats and well suited to the Seagrass Meadow's saltwater conditions. The April 2026 collection from a Spring Hill tidal ditch confirms that local Florida populations of this species tolerate the brackish end of its salinity range.
Brachidontes exustus attaches to hard surfaces using byssal threads, forming clusters on rock, shell, mangrove root, and other firm substrates in the intertidal to shallow subtidal zone. It can tolerate periodic emersion and variable salinity. In miniBIOTA, the mussels occupy hard surfaces within the Seagrass Meadow, where they filter the water column from a fixed attachment point. No specific microhabitat use within the biome has been documented beyond hard-surface attachment.
Brachidontes exustus is a filter feeder. It draws water through its gills using cilia, capturing phytoplankton, suspended microbes, bacteria, and fine organic particles. Filtered particles are transported to the mouth for digestion; water is expelled through the exhalant siphon. In miniBIOTA, no direct feeding observations have been made; diet is inferred entirely from species biology and bivalve filter-feeder classification.
Brachidontes exustus reproduces by broadcast spawning: males and females release gametes into the water column, where fertilization occurs. Developing larvae spend a planktonic phase before settling and attaching to hard substrate as juvenile mussels. Spawning can occur multiple times per year under favorable conditions. In miniBIOTA, no reproduction has been confirmed. Successful recruitment would require spawning, larval survival in the water column, and successful settlement onto available hard substrate.
Brachidontes exustus is notably tolerant of salinity variation, occurring in habitats from brackish tidal ditches to full marine water. The April 2026 collection from a Spring Hill, FL tidal ditch and the subsequent drip acclimation from brackish to marine conditions demonstrates this range. It is also tolerant of warm subtropical temperatures and periodic low dissolved oxygen typical of intertidal zones. Formal tolerance measurements for temperature, pH, salinity drift, dissolved oxygen, and flow have not been taken in miniBIOTA.
The Scorched Mussel provides water-column filtration in the Seagrass Meadow, capturing suspended phytoplankton and fine particles and converting them into attached bivalve biomass. This role removes particles from the water column and deposits filtered material as feces and pseudofeces at the sediment surface, potentially contributing to local nutrient cycling. In this context, the Scorched Mussel partially fills the filter-feeding role previously held by eastern oysters, which failed in the Seagrass Meadow.
The February 20, 2026 observation noted that the mussels appeared to be outcompeting Depressed Slippersnails for hard-surface attachment space. This is an observer-level interpretation from a single observation and has not been confirmed through systematic comparison.
No other ecological interactions have been documented in miniBIOTA. The Scorched Mussel's filter-feeding role and its possible competition with Depressed Slippersnails are the two ecological patterns currently on record.
An original population of Scorched Mussels was present in the Seagrass Meadow before February 2026; no introduction date, method, or source is recorded for that founding group. The population survived the decline of the eastern oyster population and was noted as persisting more successfully than expected. On April 22, 2026, three additional individuals were collected from a brackish tidal ditch in Spring Hill, FL, drip-acclimated from brackish to marine salinity using a syringe method alongside amphipods, and introduced to the Seagrass Meadow. Video footage was recorded of the drip-acclimation process.
Three Scorched Mussels were documented in the Seagrass Meadow by February 20, 2026, having persisted more successfully than expected after eastern oyster failure; two had been seen approximately one month prior. Three additional individuals were collected from a brackish tidal ditch in Spring Hill, FL and introduced on April 22, 2026 following drip acclimation to marine salinity. The combined potential population is up to six individuals; long-term establishment and recruitment remain unresolved.
Brachidontes exustus is a filter feeder that draws suspended water through its gills using cilia, capturing phytoplankton, suspended microbes, bacteria, and fine organic particles. In miniBIOTA, no direct feeding observations have been documented; trophic role is inferred from species biology and bivalve filter-feeder classification.
Brachidontes exustus tolerates a range of salinity from brackish to full marine, as demonstrated by the April 2026 individuals collected from a brackish tidal ditch and drip-acclimated to marine conditions. Formal measurements for temperature, pH, dissolved oxygen, and flow have not been taken in miniBIOTA.
No reproduction has been confirmed in miniBIOTA. Successful recruitment would require broadcast spawning, larval survival in the water column, and settlement onto available hard substrate in the Seagrass Meadow.
Provides water-column filtration in the Seagrass Meadow, partially filling the filter-feeder role after eastern oyster decline. The February 2026 observation noted that mussels appeared to be outcompeting Depressed Slippersnails for hard-surface attachment space; this is an observer interpretation from a single observation and has not been confirmed.
Follow this species across the habitats where it currently appears in the miniBIOTA biosphere.
