Seals

Definition

Seals are marine mammals belonging to the family Phocidae (true seals) and Otariidae (eared seals), characterized by their streamlined bodies, flippers, and a lack of external ear flaps. These animals are crucial components of polar and temperate marine ecosystems, as they play significant roles in the food web, both as predators and prey, influencing the dynamics of their habitats and the health of oceanic environments.

5 Must Know Facts For Your Next Test

1. Seals are divided into two main families: true seals (Phocidae), which are more aquatic and lack external ear flaps, and eared seals (Otariidae), which are more agile on land and have external ear structures.
2. Many seal species are social animals, often found in large groups on beaches or ice floes, where they breed and raise their young.
3. Seals have a diverse diet that can include fish, squid, and crustaceans, depending on their habitat and available food sources.
4. Their adaptations for life in cold water include thick blubber for insulation, a streamlined body shape for efficient swimming, and specialized lungs that allow them to hold their breath for long periods while diving.
5. Climate change poses significant threats to seal populations as it affects their habitats, particularly in polar regions where sea ice is diminishing.

Review Questions

• How do seals adapt to their cold marine environments, particularly in terms of physiology and behavior?
  • Seals have several adaptations that help them thrive in cold marine environments. Their thick layer of blubber provides insulation against frigid waters while also serving as an energy reserve during lean times. Physiologically, seals possess streamlined bodies that enhance swimming efficiency. Behaviorally, they often haul out on ice or beaches to rest and breed, allowing them to regulate their body temperature effectively while also protecting their young.
• Discuss the ecological roles that seals play within polar and temperate marine ecosystems.
  • Seals occupy vital ecological roles in marine ecosystems as both predators and prey. As predators, they help regulate fish populations by preying on species such as herring and mackerel. This predation impacts the structure of the food web. Conversely, seals serve as prey for larger predators like orcas and polar bears, linking various trophic levels in these ecosystems. Their presence indicates the health of marine environments, reflecting changes due to factors like overfishing or climate change.
• Evaluate the impact of climate change on seal populations and how this may affect marine ecosystems overall.
  • Climate change significantly impacts seal populations primarily through the loss of sea ice habitat essential for breeding and resting. As temperatures rise and ice diminishes, species that depend on these habitats face increased mortality rates and lower reproductive success. This decline can disrupt local food webs, as fewer seals may lead to overpopulation of their prey species while simultaneously reducing the food available for apex predators. The resulting shifts in population dynamics highlight the interconnectedness of marine ecosystems and emphasize the importance of addressing climate change.

Related terms

Blubber: A thick layer of fat beneath the skin of seals that provides insulation and energy storage, helping them survive in cold marine environments.

Molt: The process by which seals shed their old fur and grow new fur, which is essential for maintaining insulation and buoyancy.

Foraging: The act of searching for and gathering food, which in seals involves diving and hunting various prey such as fish, squid, and crustaceans.