Insects: Transport, Excretion, Respiration, Regulation, Nutrition, Reproduction, and Development
If you want to know:
-The processes involved in the excretion in insects
-How insects move food and nutrients through their bodies
-How insects breathe
-How insects keep their bodies functioning consistently
-The nutrients insects need for survival
-The processes and structures involved in insect reproduction
-The typical life cycle of an insect
This page discusses these topics.


1. Insect Transport
-All multicellular organisms need complex mechanisms for moving materials necessary for life throughout their bodies
In insects, these materials may include: undigested food, nutrients, and hormones.
To move these materials, insects have many specialized organs
-Insects have a complete digestive system, meaning that digestion occurs in a tube-like structure that starts at the mouth and leads to the anus. In insects, this tube is called the alimentary canal.
2. Insect excretion
-Most arthropods, including insects, dispose of nitrogenous wastes through Malpighian tubules, which filter wastes and nutrients.

-Malpighian tubes are saclike structures in the alimentary canal. Through osmosis, wastes are extracted from the blood by the Malpighan tubules and then added to the feces, which is then removed through the anus.

3. Insect Respiration
-Most insects breathe through a network of tracheal tubes, which branch throughout the body
-Air enters and leaves the tracheal tubes through holes on the side of the bod called spiracles.
-Spiracles act somewhat like a nostril.

Image:Actias selene 5th instar spiracles sjh.jpg
Image:Actias selene 5th instar spiracles sjh.jpg

So as the insect expands its tracheal tubes, air is pulled in through the spiracles like the one shwon on this moth caterpillar. When it exhales, the air leaves the spiracle. Think of spiracles as being like your nostrils.

external image Robal.png

At number 8, you can see the tracheal tubes and the spiracle at the end.
Another good example is on page 717 of the text.
4. Reproduction
-Insects reproduce by internal fetilization
-The male sex organs excrete a sperm packet, or use an appendage to insert it directly into the female's ovary.
-The female then picks up the sperm packet, where it is taken to the ovaries
-The sperm fertilize the egg in the ovary
Finally the female lays the fertilized eggs, which will hatch later
-The key point about internal fertilization: eggs are fertilized in the mother's body, but the mother lays the eggs to hatch.
5. Nutrition
-Insects are so diverse that they contain predators, scavengers, herbivores, and other feeding types.

-Three main types of mouthparts
An insect may have one of three main mouth types, depending on its food source
-Mandibles are used to grind food, such as in an ant
-A a tube-like mouthpart used to suck up foods such as nectar, like with butterflies
-A sponge like mouthpart used to lap up food, and mix it with saliva, such as on houseflies.
The three mouth part types are well examplified on the top of page 728 of the textbook
Often, insects will use digestive enzymes in their saliva to break their food down into digestable forms.
- A good example of this is bees using chemicals in their saliva to break down nectar into honey
-Once mixed with digestive enzymes, food is digested in the digestive tract, and turned into usable nutrients.
6. Development
The growth and development of insects almost always involves metamorphosis

Two distinct types: Complete metamorphisis and incomplete metamorphosis
Complete metamorphisis is very easy to remember. Just think of the life cycle of a butterfly.
-In complete metamorphisis, the insect goes through a drastic change. It hatches as a larvae, and then forms a pupae (think of it as a cacoon) and comes out of the pupae as an adult.
Basically, complete metamorphisis involves a cacoon, and incomplete metamorphosis has larvae that look like adults.
-Incomplete metamorphosis is the other, less stereotypical form of metamorphisis. The organism hatches as a nymph, which looks similair to an adult. The nymph gradually developes into an adult, with less noticeable changes.
Look on the bottom of page 729 in the textbook to see both types of metamorphosis
As in all organisms, insects need to keep their bodies functioning consistently, aka homeostasis
-Insects have many ways to detect external stimuli, such as keen eyes and relativly strong senses of smell
-Many insects are able to detect minute changes in light and color
-Insects have chemical receptors for smell located in their mouths, but also on the antennae and legs. This means that when a fly lands on sugar water, it can taste it immediately.
-Often, insects also have ears that hear sounds high above the human voice range. Many can also detect the slightest movements in the sorrounding air. This explains why it is so hard to kill flies by swatting them- they can feel the air pushed by your hand long before you can actually swat it.