Species Description: The checkered puffer, Sphoeroides testudineus, is one of several fish species in Florida belonging to the family Tetradontidae, meaning "four teeth." Puffers have four tooth plates arranged in quadrants, with two teeth on the bottom and two on the top (Carpenter 2002). These teeth form a strong, heavy beak capable of cracking through hard prey such as mollusks and crustaceans.
Puffers are named for their ability to swell by swallowing water or air when threatened. They have no spinous dorsal fin, absent or reduced scales, sandpapery denticles on various areas of the body, and a reduced gill opening. Identification of species is determined in part through color, pattern, and the presence and number of spines and fleshy tabs, or lappets, on the skin (Robins & Ray 1986). The checkered puffer is pale tan to yellowish with a polygonal or square network of lines centered around a bulls-eye pattern on the midback in front of the dorsal fin. Lines are dark gray to olive, with small, dark brown spots on cheeks and lower sides. The abdomen is whitish and unmarked. Dark bands are present on the caudal fin.
Potentially Misidentified Species: Several species of puffers inhabit the waters of the IRL. In addition to S. testudineus, three other Florida puffer species of the genus Sphoeroides are found in the IRL.These include: the northern puffer, S. maculatus; the southern puffer, S. nephelus; and the bandtail puffer, S. spengleri.
The northern puffer is olive-gray with many black spots and 6-7 vertical gray areas on the side (Robins & Ray 1986). It has a black bar between the eyes and prickles on the skin of the tail. S. maculatus grows to a maximum length of 36 cm, slightly larger than the checkered puffer.
The southern puffer is similar to S. maculatus, but lacks the black spots on the sides and dorsal surface. Instead, pale tan rings or semicircles cover this area, and larger dark spots are variable on the sides. Dark slashes are sometimes present on the lower half of the cheek, and prickles are found on the posterior ventral surface near or at the anus.
The bandtail puffer is usually dark brown above, with pale sides and white underneath. A row of large brownish black spots extends from the chin to the caudal-fin base on the lower sides, separate from the dark dorsal color. Many tan, fleshy tabs are present near the rear of the body. At only 18 cm, the reported maximum size for S. spengleri is much less than that of the checkered puffer.
Regional Occurrence: The checkered puffer ranges from Rhode Island to Florida, Bermuda, and the southeast Gulf of Mexico to the southeastern coasts of Brazil (Robins & Ray 1986). It is common in bays, seagrass beds, tidal creeks, mangrove swamps, and into freshwater areas (Figueiredo & Menezes 2000).
IRL Distribution: The checkered puffer is distributed throughout the IRL. Most populations are found in association with seagrass beds and mangroves, although some individuals occur in rocky intertidal and hardbottom areas as well.
Age, Size, Lifespan: Information concerning the maximum age and average lifespan of S. testudineus is lacking. Growth rates vary with environmental conditions, food availability and other factors. The maximum reported size for the checkered puffer is 30 cm (Robins & Ray 1986), but most specimens are much smaller.
Abundance: Little information is available on the abundance of S. testudineus. However, it is a common species found in many estuarine habitats. Juveniles are frequently caught in seagrass beds and around mangrove roots. The checkered puffer is listed as one of eight dominant fish species in coastal waters of Yucatan, Mexico (Vega-Cendejas & de Santillana 2004).
Reproduction and Embryology: Information on the reproductive biology and embryological development of the checkered puffer is lacking. However, much work has been completed on the reproduction and culture of a similar species, the Mexican bullseye puffer, Sphoeroides annulatus (eg. Sanchez et al. 2008). The bullseye puffer is considered a total spawner, spawning only once per year in Mexico. No sexual dimorphism exists in this species, but females are identified by their swollen abdomens during the spawning season. Eggs of several puffer species are demersal and adhesive, sinking to the benthos after fertilization.
The saddled toby, Canthigaster valentini, and the sharpnose puffer, C. rostrata, both release eggs that become hidden in benthic algae (Gladstone 1987, Sikkel 1990). The grass puffer, Takifugu niphobles, lays eggs under pebbles in the intertidal zone (Yamahira 1997). Puffers lay varying numbers of eggs, depending on species, individual size and other factors. Females of S. annulatus lay 600,000 to 1,600,000 eggs per kg of fish, usually measuring less than 1 mm in diameter (Duncan et al. 2003, Sanchez et al. 2008).
Temperature: The range of the checkered puffer extends throughout temperate, tropical and subtropical waters. In addition, shallow estuarine habitats in which S. testudineus occurs likely subjects the fish to large temperature fluctuations seasonally, during tidal cycles, episodes of heavy precipitation and runoff.
Salinity: Puffers have the ability to regulate the osmolality, or ionic concentration of substances such as sodium and chloride, in their plasma. This capacity allows them to thrive in a wide range of salinities. The checkered puffer is common in waters ranging from 0 to over 67 ppt (Lopes 2000, Vega-Candejas & de Santillana 2004).
Trophic Mode: Puffers are voracious predators, using their powerful beak-like teeth to crush hard-shelled prey. The diets of checkered puffers in south Florida vary with size (Targett 1978). Puffers 72-149 mm feed mostly on gastropods, brachyuran crabs and small numbers of bivalves. Fish larger than 150 mm consume mostly crabs and bivalves. Other prey items frequently found in gut contents of S. testudineus include amphipods, hermit crabs, seagrasses, detritus, isopods, sipunculids, barnacles and tunicates.
Predators: Although some larger fishes and birds likely prey on puffers, the ability of these fishes to swell with water or air reduces predation risk by greatly increasing overall body size.
Associated Species: The checkered puffer has no known obligate associations. However, as inhabitants of a variety of coastal ecosystems, checkered puffers are associated with several organisms common to mangroves, seagrass beds and rocky intertidal zones.
Special Status: Prohibited fishery in Florida. See below.
Economic History & Toxicity: During World War II, the checkered puffer became an important source of protein for people living of the east coast of the US. Its use spurred a commercial fishery that flourished for decades, based in Virginia, Maryland, New York and New Jersey (Sibunka & Pacheco 1981). Marketed as "sea squab", over 6,000 metric tons of puffer fish was landed in 1965 (Deeds et al. 2008). Today, the commercial market has collapsed, but checkered puffer is often caught by recreational anglers and fresh catch can still be found in some US fish markets (Sibunka & Pacheco 1981).
One difficulty with puffer fisheries is the prevalence of saxitoxins (STX) and tetrodotoxins (TTX) that often occur in the tissues of the fish. STX are produced from toxic dinoflagellates such as Pyrodinium bahamense (Landsberg et al. 2006), which often grow on sediments, rocks, seagrass and algae. Puffers inadvertently ingest these microorganisms when they feed on benthic macrofauna. Toxins are then sequestered in the skin, muscles and viscera of the fish (Landsberg et al. 2006). In addition to STX, TTX are found in many organisms, including: several species of puffers; the seastar, Astropecten polycanthus; the mangrove horseshoe crab, Carcinoscorpius rotundicauda; the floral egg crab, Atergatis floridus; the calcareous red alga, Jania sp.; and the California newt, Taricha torosa (eg. Simidu et al. 1987). In most cases, TTX is produced from bacteria of the genus Vibrio (Lee et al. 2000; Simidu et al. 1987, 1990).
Both STX and TTX are powerful neurotoxins that cannot be destroyed by cooking, thus causing Puffer Fish Poisoning (PFP) upon ingestion of infected tissue. Symptoms of PFP include: numbness of lips, tongue, face, hands and feet; salivation; nausea and vomiting; diarrhea and abdominal pain; motor dysfunction and speech difficulties; seizures; paralysis; and death, usually resulting from respiratory failure (Benzer 2007). Toxins from S. testudineus have even been controversially reported as causes of zombification in Haiti (Davis 1988, Littlewood & Douyon 1997). Some puffers in the IRL have been found to contain both STX and TTX, resulting in several cases of illness and a few reported deaths from PFP (eg. Deeds et al. 2008). In April 2002, the Florida Fish and Wildlife Conservation Commission (FWC) prohibited the taking of puffers from the waters of Volusia, Brevard, Indian River, St. Lucie and Martin counties. The ban remains in effect as of the date of this report.
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