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Senses, Signals and Sea Turtle Hatchlings

Use zoo conservation data to explain how senses lead to behavior and memory.

Hatchlings and light

Read the passage and study the table. Then answer the questions.

Lights Out for Hatchlings

1Each summer, the conservation team at Bayside Zoo works with wildlife biologists to protect sea turtle nests on a nearby beach. Sea turtle hatchlings usually leave the nest at night. On a natural beach, the open sky over the ocean is often a little brighter than the dark dunes and trees behind the beach. Light-sensitive cells in a hatchling's eyes detect the difference, nerves carry signals to its brain, and the brain sends signals that move its flippers. Most hatchlings crawl toward the brighter, lower horizon.

2Biologists on the team noticed tracks heading inland near houses with porch lights. To test lighting, they used a round arena with a sand floor in a dark room. A dim, glowing panel on one side copied the night sky over the ocean. On the opposite, land side they could place a lamp. Both lamps were cool LEDs set to the same power, so neither one warmed the sand. Each hatchling was placed in the center once, its direction was recorded, and it was released on the beach that same night. Every setup used 20 hatchlings that had never been tested before.

3Zoo keepers also use senses to train animals for health checks. A young river otter named Pip was learning to swim to a flat rock station when a keeper blew a whistle. Each time Pip reached the station within 5 seconds, the keeper gave a small piece of fish. Every training day, at the same time before lunch, the keeper blew the same whistle at the same loudness 10 times. Pip ate the same amount of food each day.

Arena Tests (20 hatchlings per setup)
SetupLamp on land sideCrawled to ocean sideCrawled to land side
1None182
2White LED515
3Amber LED164
1.
Match each part of the model to what it is in Setup 2.
  1. Stimulus
  2. Sense receptors
  3. Nerves
  4. Behavior
  1. A. Carry signals between the eyes, brain and flippers
  2. B. The hatchling crawls toward the land side
  3. C. Light from the white lamp
  4. D. Light-sensitive cells in the hatchling's eyes
2.

In Setup 1, what percent of the hatchlings crawled to the ocean side?  %

3.

How many fewer hatchlings crawled to the ocean side with the white lamp than with no lamp?   hatchlings

4.
Which explanation best fits the results of Setup 2?
  • A. Their eyes detected the bright lamp, and their brains steered them to it.
  • B. The hatchlings found the ocean side by smell and ignored the light.
  • C. The lamp warmed the sand, and the hatchlings crawled toward the heat.
  • D. The hatchlings learned in earlier tests that the land side was safer.
5.
A beach town wants to help hatchlings reach the ocean. Based on the arena tests, which change would most likely help the most?
  • A. Keep the white lights, since hatchlings follow the smell of the ocean
  • B. Add brighter white lights on the dunes so hatchlings can see the path
  • C. Replace bright white porch lights with amber lights or switch them off
  • D. Change the amber lights to white ones, which hatchlings seem to avoid

Training with a whistle

Use the graph and paragraph 3 to answer the questions.

Pip's Whistle Training0246810Day 1Day 2Day 3Day 4Day 5Training dayTimes at station (of 10)
6.

How many more times did Pip reach the station on Day 5 than on Day 1?   times

7.
What best explains the change in Pip's responses from Day 1 to Day 5?
  • A. Pip got hungrier each day because it ate less food.
  • B. Pip's brain stored memories linking the whistle with fish.
  • C. The keeper blew the whistle a little louder on each new day.
  • D. Pip's ears grew larger, so the whistle was easier to hear.
8.
In Pip's training, which part is a sense receptor?
  • A. The piece of fish from the keeper
  • B. Pip swimming to the station
  • C. The sound of the whistle
  • D. Sound-sensing cells in Pip's ears
9.
Sort each behavior.
A hatchling crawls toward the brightest horizon on its first night.Pip swims to the rock station on Day 5 when the whistle blows.You blink when a gust of sand blows toward your eyes.A dog runs to the door when it hears its leash jingle.Your pupils get smaller when you step into bright sunlight.You recognize a friend's voice on the phone before they say their name.
Happens without learningDepends on a memory of past experience
10.
Towns near nesting beaches are asked to change bright lights during hatching season. Write a claim about why, give evidence from the arena table, and explain your reasoning. Describe the path from the stimulus to the hatchling's behavior.