Today, diamondback terrapins (Malaclemys terrapin) are fairly common along the east coast United States. They were practically eaten out of existence earlier this century, but fortunately these heavily exploited turtles have made a good recovery and have re-established themselves over much of their former range.
Few people in Southern California keep diamondback terrapins, but we've been keeping these turtles for eight years. Our first diamondback terrapin, a female, came from our veterinarian and was quickly named Terry by the kids. A mate for Terry was obtained through a CTTC member, and was probably from a commercial wholesaler. Later, we acquired a second younger male from New Jersey and a second female that had been raised from a hatchling by another Club member.
Diamondback terrapins show a wide morphological variation. Seven subspecies are recognized that vary in their coloration, markings and behavior as well as their ranges. For instance, there is a Florida form of the diamondback terrapin which is slate-black in color with a widened head and jaw for eating barnacles off the roots of mangrove trees. Diamondback terrapins may change in appearance as they get older. For example, our female Terry was very dark when she was young; now her shell color has lightened up a lot. Because these turtles were collected and transported to be commercially raised for food in the past, specimens of some subspecies derived from escaped or released captives may be found outside their expected range and may have influenced the appearance of local populations.
Diamondback terrapins have a wide tolerance of salt in their water, and are the only North American turtles native to brackish (salty, but not as salty as the ocean) waters. They live in salt marshes as far north as Cape Cod, all the way down to the Florida Keys and around the Gulf Coast from Florida to Texas. Salt concentrations in their wild habitats have been measured at 28 parts per 1000. Some of their marshes are totally tidal while some are fed by freshwater springs. Wild hatchlings may spend their first years upstream in creeks. These creeks are sometimes brackish and sometimes relatively fresh water. As the hatchlings age, they seem to move down to the salt marshes where nutrients are plentiful and there are good nesting sites. Surfers have found grown terrapins swimming beside them in the Atlantic Ocean.
Our terrapins are housed indoors in large aquariums with basking areas, filter systems, incandescent lights and Vitalites. We add salt to their water, 1/4 cup salt to 20 gallons water, and slightly acidify it (to pH 6.8) using commercial kits available at tropical fish stores. Terry, our egg-laying female, behaves oddly when it's time for her to lay her eggs. At the appropriate time of year, when she claws and scratches at the glass wall of the aquarium we place her outside in our box turtle enclosure so she can dig her nest and lay eggs. She lays her first clutch in January, with up to 3 more clutches laid about a month apart.
In years past, our incubation method was very casual. We would put the eggs on a damp paper towel in a margarine tub and simply leave them in a cupboard over the refrigerator. Last year (1992) was the first year that we used an incubator for our turtles' eggs. The incubator was a 10-gallon aquarium heated with 15 and 25 watt incandescent light bulbs to keep the temperature at 80°-83°F (26.6°-28.3°C). The eggs were placed on moistened paper towels in margarine tubs with tight fitting lids with no holes. A dish of water was placed in the incubator for added humidity. Th containers were checked regularly to ensure that the paper towels remained damp.
Two clutches of five eggs were incubated for about 90 days. Two eggs hatched from the first clutch; all five eggs hatched from the second clutch. Two other clutches were found too late to incubate. While cleaning up in the box turtle yard one day, we were surprised to find a tiny live terrapin among a clutch of dried out eggs! I brought it inside and put it in water. It started to swim right away, and has thrived. We named it Serendipity.
We start the hatchlings on live brine shrimp and then switch them to Tetra Reptomin. The older terrapins eat Purina trout chow and turtle "meat-loaf".