Streptocephalus mackini, commonly known as the Chihuahuan Desert fairy shrimp, belongs to the family Streptocephalidae. This species can be found in a diverse range of habitats, including ephemeral pools in arid grasslands, predominantly during warmer seasons of the year. Although often associated with habitats with low to moderate dissolved solids, Streptocephalus dorothae is not limited solely to these environments. It can be frequently observed in southern, western, and Midwest regions of North America.
Anatomy: The characteristics outlined below may exhibit variations influenced by environmental conditions, population dynamics, and the organism's age.
Head:
Second Antenna:
Male: The shrimp has a long, extended part (peduncle) that doesn’t have a swelling (pulvinus), but instead, it has about 8 cone-shaped bumps of varying sizes on the inner side of its far end. The inner upper side of the base of the ‘hand’ has a stout spine-like structure that points forwards. It has a triangular projection (spur) with a tip that has a swollen part near the tip, ending in a somewhat pointed (subacuminate) shape. There is a thin layer or plate on the side (lateral lamella) that forms a sharp angle with the far end of the ‘thumb’ and the spur. This arrangement creates a cavity in the middle-lower part. The far end of the ‘thumb’ is unarmed (inerm), bent (geniculate), with a noticeable elbow on the lower side, and the tip is pointed (acuminate). The ‘finger’ has two bends (bigeniculate), with two ‘teeth’ on the inner upper side of the near part. The far ‘tooth’ is wide at the base, with its front margin extended forwards and upwards into a pointed (acuminate) structure. The near ‘tooth’ is shorter, somewhat pointed (subacuminate) and slanted forwards, with its tip part projecting beyond the back margin of the far ‘tooth’. The ‘finger’, at the first bend, has a wide upper layer (dorsal lamella), which is narrow at the second bend. The tip of the ‘finger’ is pointed, with a swollen part near the tip that is armed with a spine-like structure on the side, pointing forwards and downwards.The front appendage on the head is simple, short, and usually has two lobes at the tip.
Female: Reduced second antenna
Thorax:
Dorsolateral Process:
Male: Absent
Female: Absent
Thoracopods:
Consistent between sexes with fine setae on the edges of the limbs.
Reproductive Segments:
Male: A pair of penes.
Female: Cone-shaped brood pouch. The ovaries have two branches (biramous) and vary in length, extending from the 5th to 10th segments of the thorax (the part of the body between the head and the abdomen) to the 5th to 6th segments of the abdomen.
Cyst:
The cysts are round and decorated by ribs forming many-sided (polygonal) areas.
Abdomen:
No unique features, same between sexes.
Tail:
Cercopods:
The tail appendages (cercopods) are separate and are set with bristly hairs (setae) along the middle and side borders.
Morphology:
Size: 2.0cm to 2.5cm in length, contingent on prevailing environmental conditions.
Coloration: The body is typically transparent in coloration but can have tints of blue, yellow, green, and brown.
Captivity and Growth:
Growth is influenced by multiple factors such as temperature, salinity, and care. These temperature ranges are based on our experience but do not represent the maximum or minimum.
Hatching Temperature Range: 68 to 78°F.
Temperature Range for Adults: 68 to 78°F.
Hatching: At temperatures of 72 to 78 Fahrenheit, nauplii appear after 24 to 48 hours.
Growth Rate: This species has a moderate growth rate reaching sexual maturity at around 10 to 14 days with an average lifespan of 8 to 10 weeks.
Behavior: This species prefers to swim in open water, feeding on microorganisms in the water column, and is constantly swimming more or less in a stationary manner.
Reproduction: Males use their second antenna to latch onto the females, taking only but a few seconds to mate.