Lecture 13 - Sensory Ecology

Question 1

What happens to molecular complexity with distance from the source?

Answer 1

It declines.

Question 2

What are sensors?

Answer 2

Accessories to the nervous system that act as transducers.

Question 3

Name an organism that uses an electrosensing.

Answer 3

Freshwater crayfish

Question 4

What is flow detected by?

Answer 4

Surface hairs

Question 5

Describe the detection of flow on coral planula.

Answer 5

Detect turbulence and flow using cilia.

Move towards the source of the sound.

Question 6

Describe the detection of flow in copepods.

Answer 6

Use antennae.

Allows them to lock into the water that they’re surrounded by and detect small-scale vibrations in the water.

Question 7

What is vibration detected by?

Answer 7

Accelerometers

Question 8

Describe how crabs detect vibration.

Answer 8

Fuse sand grains together, creating a large crystalline structure which will vibrate relative to the crab.

Question 9

Give some differences in fish eyes compared to the eye structure of other invertebrates.

Answer 9

• The lens is solid in fish
• Muscles move the lens forward and backwards, and do not stretch it.
• Fish have a fixed pupil.

Question 10

What is the role of

a) Rods?
b) Cones?

Answer 10

a) Rods = vision in low light, deep sea.

b) Cones = resolution, colour discrimination.

Question 11

True or false:

The ratio of rods and cones found in the retina is constant in fish.

Answer 11

FALSE.

The ratio of rods and cones varies depending on where fish live.

Question 12

Describe the work of Siebeck et al (2010).

Answer 12

Described ultraviolet vision in shallow water species.

There are unique marks fish can see that are used for individual recognition, e.g. mate recognition.

Question 13

Give the three pigments found in cones.

Describe the type of light they sense, and what sort of species they are found in.

Answer 13

1) Porphyropsin - yellow-red light, found in shallow species.
2) Rhodopsin - blue-green light, found in deeper water species.
3) Chryopsin - deep blue light, found in deep sea species.

Question 14

Describe a visual adaptation in striped marlin.

Answer 14

The retina gives high acuity and colour recognition looking forward and upward, and blue vision for dim objects looking down.

Question 15

Describe a visual adaptation of marlin and billfishes.

Answer 15

Can warm their eyes.

Eyes then work faster than cold-blooded prey species.

Question 16

Describe a visual adaptation of lemon sharks.

Answer 16

Undergo an ontogenetic shift from Porphyopsin pigments as juveniles in mangroves, to rhodopsin pigment as adults in deeper waters.

Question 17

Describe a visual adaptation of Engraulids (eels and salmons).

Answer 17

Can detect polarised light.

Use it as a compass, allowing them to detect the direction for long-distance migrations.

Question 18

What is the name of receptors involved in electroreception?

Answer 18

Ampullary receptors

Question 19

What are Ampullae of Lorezini?

Answer 19

Hair cells with a cap of conductive gel, allowing the fish to detect and electrosense.

Question 20

What are Ampullae of Lorezini found in?

Answer 20

• Lampreys
• Sharks
• Coelocanths
• Sturgeons
• Bony fishes

Question 21

Where can variation in the magnetoscent be detected in fish?

Answer 21

• From regional features, e.g. volcanic islands, with high levels of magnetic matter in rocks
• From local features, e.g. minerals in the seabed with magnetic signals.

Question 22

Why are sharks and rays vulnerable to detection?

Answer 22

They have sensitive electroreception which disrupt the magnetic field.

Question 23

Give some uses for chemoreception.

Answer 23

• Finding food
• Recognising food
• Detecting and avoiding predators
• Locating habitat
• Communication

Question 24

Describe chemoreception structures in fish.

Answer 24

• Have paired olfactory chambers, each with incurrent and excurrent nostrils.
• Olfactory chamber lined with highly folded olfactory epithelium; high density of olfactory receptor cells as water passes through canal.

Question 25

What is mechanoreception?

Answer 25

The detection of physical movement.

Question 26

What is mechanoreception detected by?

Answer 26

Specialised cilia bundles that are orientated in different directions.

Question 27

How does mechanoreception work?

Answer 27

Relative movement of kinocilium and stereocilia generate nervous impulse (greater when moving in the same direction).

Question 28

How can animals detect the intensity of a disturbance in mechanoreception?

Answer 28

Have different lengths of stereocilia. If the disturbance is faint, the longest will move only. But intense disturbance causes movement of all the hair cells.

Question 29

What is the lateral line system used for?

Answer 29

Motion detection (e.g. current detection, obstacles, prey, predators, shoalmates)

Question 30

What is the benefit of the lateral line system being within a canal?

Answer 30

Means no flow is generated from its own swimming, but any other movement disturbs the water flowing naturally over the skin, generating differential movement of water.

Question 31

What is an otolith?

Answer 31

• Free floating
• High density of hair cells arranged in bundles pointing in different directions around the otolith.
• Otolith vibrates relative to the fish; fish can detect direction of the sound.