Conjoined fetal twins in a harbor seal (Phoca vitulina)

This article describes the first known case of conjoined twins in a harbor seal. The case was documented in the Salish Sea region where harbor seals are often used as indicators of contaminant levels. However, researchers say their findings do not support that this anomaly was due to any common contaminants and hypothesize that the twinning was caused by disordered embryo migration and fusion. 

FIGURE 2. Dorsoplanar computed tomography image of conjoined fetal twins in a harbor seal (Phoca vitulina) from San Juan County, Washington, USA. The arrow points to the fusion of the spines.
FIGURE 2. Dorsoplanar computed tomography image of conjoined fetal twins in a harbor seal (Phoca vitulina) from San Juan County, Washington, USA. The arrow points to the fusion of the spines.

Abstract

In July 2013, a stranded harbor seal (Phoca vitulina) died giving birth to conjoined fetuses. The twins were joined at the abdomen and thoracolumbar spine with the vertebral axis at 180°. The cause of this unique anomaly—a first for this species—was not identified.

Citation

Olson JK, Gaydos JK, McKlveen T, Poppenga R, Wicinas K, Anderson E, & Raverty S. 2015. Conjoined Fetal Twins in a Harbor Seal (Phoca vitulina). Jrnl of Wildlife Diseases, 52(1):173-176.

 

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About the Author: 
Jennifer K. Olson, 1,6; Joseph K. Gaydos, 2; Tori McKlveen, 3; Robert Poppenga, 4; Kay Wicinas, 1,2; Elizabeth Anderson, 1,2; and Stephen Raverty 5: 1 The Whale Museum, 62 First Street N, PO Box 945, Friday Harbor, Washington 98250, USA; 2 SeaDoc Society, UC Davis Karen C. Drayer Wildlife Health Center–Orcas Island Office, 942 Deer Harbor Road, Eastsound, Washington 98245, USA; 3 VCA Veterinary Specialty Center of Seattle, 20115 44th Avenue W, Lynwood, Washington 98036, USA; 4 California Animal Health and Food Safety Toxicology Laboratory, UC Davis School of Veterinary Medicine, 620 W Health Sciences Drive, Davis, California 95616, USA; 5 Animal Health Center, 1767 Angus Campbell Road, Abbotsford, British Columbia, Canada V3G 2M3; 6 Corresponding author (email: jennifer@whalemuseum.org)