Overview
The False Spike is a medium-sized freshwater mussel native to the Guadalupe River basin in Texas. The False Spike was once considered common wherever it was found; however, beginning in the early 1970s, the species began to be regarded as rare throughout its range and eventually was indicated that no living populations were known until 2011 the discovery of 7 live False Spike in the Guadalupe River, near Gonzales, Texas, was the first report of living individuals in nearly four decades.
Scientific Name
Identification Numbers
Characteristics
Habitat
The False Spike occurs in larger creeks and rivers in moderate to slowly flowing water with heterogeneous mixtures of sand, gravel, or cobble heterogenous substrates. The species is not known to tolerate impoundments or reservoirs. The False Spike requires flowing water with very low salinity (<2 ppt) and adequate dissolved minerals (Ca+) to support shell growth.
A natural body of running water.
Physical Characteristics
The False Spike is a medium-sized freshwater mussel with an elongate-oval to sub-rhomboidal shell. The shell’s beaks are slightly elevated above the hinge line with strong double-loop sculpturing on the umbo. The shell disc typically is sculptured with pustules, dorsal-to-ventral parallel grooves, and slight flutes on the posterior field.
Measurements:
Length: Usually up to 5 inches (132mm), but individuals greater than this length have been collected.
Shell colors range from yellow-green to brown, to black, sometimes with greenish rays. The interior shell surface (nacre) is typically white and iridescent.
Life Cycle
Males release sperm into the water column, which is taken in by the female fertilizing her eggs. The developing larvae are held by the female until they mature and are ready for release. The mature larvae, called glochidia, are released in proximity to a fish host and attach to the host’s gills or fins. Glochidia that fail to attach to a suitable host or attach to the wrong location will die. Attached glochidia encyst or implant into the host and develop into juvenile mussels over a period of weeks or months. Once fully developed, the juveniles excyst (break away) from the host and settle on the stream bottom leaving their host relatively unharmed.
No age at maturity information exists for this species. However, preliminary and ongoing shell sectioning studies suggest that the species has a maximum life span of about 17 years and frequently lives only for about 10 years.
False Spike are short-term brooders (tachytictic). Two fish host species have been identified for the False Spike, including the red shiner (Cyprinella lutrensis) and blacktail shiner (Cyprinella lutrensis), but other host fish for the species likely exist.
Food
Like all other freshwater mussel species, False Spike are filter feeders that feed and survive on organic particulate matter, bacteria, and algae that are filtered from the water column. Juvenile mussels live in the sediment and most likely feed interstitially rather than from the water column, using the relatively large muscular foot to sweep organic and inorganic particles found among the substrate into the shell opening.
Geography
The False Spike is a Guadalupe River Basin endemic and known to occur in the mainstem Guadalupe River between Gonzales and Victoria, Texas. Until as recently as 2011, the False Spike was thought to be extinct prior to the re-discovery of the species in the Guadalupe River near Gonzales.
Timeline
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