1. A submersible is needed because the extreme pressure at the bottom of the ocean would crush a regular vessel or human body, and it provides life support and protection in an environment with no light, near-freezing temperatures, and no breathable air.
2. As the submersible approaches the twilight zone (300m deep), light levels decrease significantly until it becomes nearly dark, and the water temperature drops sharply from surface warmth to near-freezing cold.
3. The deep sea squid differs from its surface-dwelling relatives by having much larger eyes to capture minimal light, often possessing bioluminescent organs for communication or camouflage, and typically having a more gelatinous, flexible body adapted to high pressure and low energy environments.
4. Two specific aspects of hatchet fish body design that allow invisibility are: 1) Their sides are covered with mirrored, silvery scales that reflect surrounding dim light, blending them into the background; 2) They have ventral bioluminescent photophores that match the faint downwelling light, eliminating their silhouette when viewed from below.
5. Many animals in the dark zone have red pigment because red light does not penetrate to those depths; in the absence of red wavelengths, red pigment appears black or dark gray, making the animal less visible to predators and prey that rely on vision.
6. Animals like the hairy angler depend on highly sensitive lateral lines to detect water vibrations and movements, and on acute chemoreception (smell/taste) to locate prey in complete darkness where sight is useless.
7.
a. Attracting Prey: The deep sea angler uses a bioluminescent lure (esca) dangling from a modified dorsal fin ray to mimic small prey or attract curious organisms in the dark.
b. Locating a Mate: The deep sea angler relies on chemical signals (pheromones) released into the water to communicate with potential mates over long distances in the vast, dark environment.
Parent Tip: Review the logic above to help your child master the concept of blue planet open ocean worksheet.
