Transcript AngelfishSenses - The Angelfish Society

How do Angelfish
Sense their World?
A Presentation for The Angelfish Society
March 16, 2008 Meeting
By Tamar Stephens
Have you ever wondered…?





If you live in the water, is it better to be warm
blooded or cold blooded?
Do angelfish have ears?
What is the lateral line?
Do angelfish see color?
Do angelfish have noses?
This presentation will give you an overview of how
angelfish sense the world around them.
If you feel cold…


If you feel cold, your body
responds by producing more
heat to keep the body
temperature at a fairly constant
temperature right around 98.6°F.
If you regulate your temperature
internally, you are what we call
an “endotherm” – or warmblooded.
If an angelfish feels cold…



If an angelfish feels colder surroundings, its body does
not generate heat to keep it warm. Instead its body
temperature will drop to the surrounding temperature.
Angelfish are “ectotherms.” (Huh? What’s an
ectotherm?)
If the body temperature is regulated by the surrounding
environment a creature is an “ectotherm” – more
familiarly called cold blooded..
It doesn’t take much energy to heat
air!



Your body stays very close to 98.6°F
regardless of the surrounding
temperature.
If you stand in 70°F air, it doesn’t take
much to heat the air that is close to your
body. With a light jacket to capture a
thin layer of air, you can be comfortable
in a wide range of temperatures.
A polar bear’s coat allows it to maintain
its body heat in temperatures down to 50°F and colder!
Is it better to be warm blooded or
cold blooded if you live in the water?

It takes a lot more energy to heat water than air. If you jump
into cold water, you lose body heat very rapidly.

Most creatures that live in the water have their body temperature
regulated by the surrounding water. It takes tremendous energy
to generate the heat to warm up the water or to maintain a body
temperature higher than the surrounding water! So except for
large marine mammals and a few types of large fish, waterdwelling animals are adapted to adjust to their environment’s
temperature.

One consequence is that most fish live in a fairly small
temperature range. Angelfish generally do best between about 75
to 85 degrees F, and they don’t do well with sudden temperature
changes!
Do angelfish have ears?
Well, yes they do!



You won’t see their ears, because angelfish do
not have external ears. Their ears are internal!
Sound travels very well through water – much
better than through air.
Sound vibrations in the water will transmit
through the fish’s body to the ear.
Ear structure

The upper section of the ear (called the pars superior)
has three semicircular canals that give fish its sense of
balance. The canals are filled with fluid and have
sensory hairs that are stimulated by rotational motion
of the fluid.

The lower section (called the utriculus) senses sound.
Vibrations of the utriculus stimulate surrounding hair
cells to vibrate, a lot like our ears.
Fish ear structure
Pars superior –
sense of balance.
Utriculus – sense
of sound
Figure is a diagram of a gourami inner ear. Source:
http://www.life.umd.edu/biology/popperlab/background/index.htm
What is the lateral line?
Have you ever noticed a curved row
of dots on your angelfish?
Yellow
arrow
points to
the lateral
line.
(Photo is of a
black crossover
female, courtesy
of Gil Repetto)
Here’s another example
Lateral Line
(Wild angelfish photo from Bob Barone)
And one more
Lateral line
(Photo from
phenotype
library. Sorry,
name of
contributor not
known.)
The lateral line is sort of a cross
between hearing and feeling.

The lateral line consists of a series of fluid-filled
ducts that sense pressure or vibrations. As the
ducts are stimulated in sequence, the angelfish
can sense the direction of the stimulus. This
allows it to sense the motion of another fish and
the direction from which it is coming.
Do angelfish see color?
Photo of leopard male from Gil Repetto
Vision in fish
Sorry, I don’t have information specific to angelfish. So
this is general information about fish vision.
 Fish in general have a good sense of vision, on a par
with human vision.
 Many fish can see color.
 A fish’s eyes are different from ours. We have a convex
lens. A fish’s lens is spherical. The spherical shape has
a higher refractive index, which enables them to see
better under water.
 They focus by moving the lens in and out, instead of
changing its shape like we do.
 But do angelfish see color?
Anecdotal evidence that angelfish
see color



I read on a forum some time ago someone describing
letting her fish select which kind of food they wanted.
She would hold up the different containers, each a
different color, and the angelfish would gather by the
food container that they selected.
I have observed my fish act startled if they see me
appear in new clothing in a color they aren’t accustomed
to seeing me in.
So, based on these anecdotal bits of information, I think
angelfish do see color. (Maybe in a future presentation
we can look at how researchers investigate the ability of
fish to distinguish colors – and you can do a study on
color vision in angelfish!)
Do Angelfish have noses?



Fish in general have a a well-developed sense of
smell.
They don’t have noses, but they do have two
nostrils - “olfactory rosettes” - one on each side
of the head. They are not connected to the
throat as in humans. They are not obvious in
angelfish to the casual observer.
(Sorry, no photos. You would need a good close
up photo to see the nostrils.)
Do they have a sense of taste?


Yes!
Fish have taste buds on their lips, tongue and
mouth.
“Feeler” Fins


Every now and then someone new to angelfish
will ask a question on a forum about the “feeler”
fins. Of course, those of us who are more
experienced know these are more properly called
“ventral” fins, or ventrals for short.
But there is a nugget of truth to in referring to
them as “feeler” fins.
Ventral fins allow the angelfish to
“feel” things below them.

Angelfish can feel the
contours of the bottom
of their environment
(pond, river, aquarium)
as the tips of the
ventrals brush against
sediments, rocks, or
vegetation. This can be
very useful in the dark.
Photo from phenotype library.
Contributor not known.
The End
I hope you enjoyed this presentation!
Now back to the meeting chat room for
discussion!