Researchers from the University of Hawaii have cracked a 140-year-old question about how Antarctic sea spiders care for their eggs. The findings, published in Ecology, shed new light on the distinctive reproductive habits of these remote marine arthropods.
Sea spiders are a broad group of marine arthropods found in oceans worldwide. While most species stay small, Antarctic relatives exhibit remarkable gigantism, reaching lengths of up to about 51 centimeters. This extreme size difference is a well-documented phenomenon in polar seas and highlights how extreme environments can drive unusual growth patterns.
Unlike many sea spider species that carry eggs openly until hatching, Antarctic forms show a different strategy. For more than a century, scientists wondered where the larvae are sheltered during development. The new work confirms that Antarctic sea spiders tend to protect their offspring by keeping eggs hidden rather than bearing them openly, a finding that helps explain how these animals survive in the harsh polar waters.
To observe these habits, researchers conducted careful fieldwork in McMurdo Sound, Antarctica, collecting samples by hand and then studying them in controlled laboratories. This approach allowed precise observations of the egg-bearing behavior and the surrounding microhabitats that support early development.
The observations revealed a simple yet effective strategy: giant Antarctic sea spiders tuck their larvae under stones and then cover these sites with moss. The moss camouflages the developing embryos and provides shelter from predators, offering a stable microenvironment that supports survival through the vulnerable early stages. This behavioral adaptation complements the spiders’ large body size, giving them a robust reproductive niche in one of the world’s most challenging seas [attribution: Ecology journal].