DRAGONFLY LIFE CYCLE
INSTRUCTIONAL MATERIALS
DRAGONFLY LIFE CYCLE WHEEL
HOW TO USE
Print, cut out and laminate the printable a DRAGONFLY life cycle wheel. (or paste in a card stock for durability)
Show each stage to your students and explain to them the development in each stage.
Print and give your students a copy and let them do their own DRAGONFLY life cycle wheel.
For older students (DRAGONFLY life cycle wheel activity)
Divide the class depending on the number of students.
Decide which group goes first.
Have the representative from the group spin the spinner.
Note where the spinner indicator lands. ( eggs, nymphs, molt, dragonfly) and pose a question about that area to the group. If the group answers the questions correctly, award it a point.
Then have the next group turn the spinner and ask the group a related question. Give a point if the question answered correctly.
Give each group five chances. In case of a tie, choose a life cycle stage and ask a question. Each of the group participating in the tie breaker write down the answer. Give a point for each correct answer.
Recognize all the students for their participation.
DRAGONFLY CARDS
Print and give your students a copy and let them do their own DRAGONFLY life cycle wheel.
For older students (DRAGONFLY life cycle wheel activity)
Divide the class depending on the number of students.
Decide which group goes first.
Have the representative from the group spin the spinner.
Note where the spinner indicator lands. ( eggs, nymphs, molt, dragonfly) and pose a question about that area to the group. If the group answers the questions correctly, award it a point.
Then have the next group turn the spinner and ask the group a related question. Give a point if the question answered correctly.
Give each group five chances. In case of a tie, choose a life cycle stage and ask a question. Each of the group participating in the tie breaker write down the answer. Give a point for each correct answer.
Recognize all the students for their participation.
DRAGONFLY CARDS
OBJECTIVE
Help the students visualize the life cycle of a dragonfly.
HOW TO USE THE CARDS
These could be laminated back to back or individually.
Show each card to your students and explain each stage of the dragonfly life cycle development.
DRAGONFLY LIFE CYCLE COLORING/ SORTING WHEEL
Show each card to your students and explain each stage of the dragonfly life cycle development.
DRAGONFLY LIFE CYCLE COLORING/ SORTING WHEEL
Learning objectives
To identify the stages of a dragonfly life cycle.
To identify the correct sequence of the life cycle of a dragonfly.
To familiarize about the life cycle of an dragonfly.
To develop coloring skill.
Dragonfly worksheet 1
Learning objectives
To identify the stages of a dragonfly life cycle.
To identify the correct sequence of the life cycle of a dragonfly.
To familiarize about the life cycle of a dragonfly.
To develop coloring skill.
To develop writing skill.
HOW TO USE
Print and give your students a copy. Explain to your students the directions written in the worksheets.
Monitor your students while doing the activity.
This could be a group or individual activity.
Dragonfly life cycle worksheet 2
Learning objectives
To identify the stages of a dragonfly life cycle.
To identify the correct sequence of the life cycle of a dragonfly.
To familiarize about the life cycle of a dragonfly.
To develop coloring skill.
HOW TO USE
Print and give your students a copy. Explain to your students the directions written in the worksheets.
Monitor your students while doing the activity.
This could be a group or individual activity.
Dragonfly
The dragonfly owing to its position in the food chain, is not scared... so if you find one flying over to you and sometimes looking to you in the eye for a few moments, don't be surprised or shocked. It's what it does... look with its 30,000 eyes to find food and mates. While 30,000 is an approximate number, it is the number of ommatidia that dragonflies have within their compound eyes. Like all arthropods, dragonflies have compound eyes, only they are a little more specialized, suited for a born predator.
When dragonflies see, they don't exactly see... they more sense. Sense movement at a much wider angle under any human could ever imagine. The reason being, its eyes are ball-like and see at a complete 360 degree span. Each ommatidia, called Ommatidium in singular, is an eye in itself, capable of seeing anything right in front of it. This helps the dragonfly movements anywhere around it.
Furthermore, the dragonfly has a flattened area right in front of its eyes with a concentration of eye cells that see directly in front. This helps it see the little mosquito as it flies around, so it cab home in on its meal. Other predators of the arthropod family like the praying mantis and the best fliers like bees have similar flattened fronts to help them see better as they fly.
The body of the dragonfly is supported by two pairs of extremely powerful wings that help it float at the slightest breeze and can flap fast and hard enough to hover even against a strong head wind. Here again, although its wings are transparent and seem quite frail, you'll find they're a whole lot stronger than they might seen at first sight. The construction of the wings and and the fact that they are not joined like those of butterflies, and can operate independently, helps the dragonfly fly and run a neat little air show on its own, capable of flight in all directions, up, down, left, right, forwards and even backwards. Nope, the hummingbird is not the only one that can go on the reverse gear.
The surfaces of dragonfly's wings are not smooth. They have small pockets like ridges that catch even the slightest gust of wind to take flight. Although the rough surface poses a certain degree of aerodynamic drag, the dragonfly can move fast enough, and more importantly have enough control in flight to make sure if it catches sight of its meal. It's as good as eaten. Not many an insect escape its six legs once the chase begin, as it out-flies the prey and grabs it using its legs and eat them at ease. To make it as simple as possible, the legs are positioned in such a way that they form a pouch like shape. This helps grab prey leaving them with very little chance of escape.
As the dragonfly flies a lot, it needs both to heat up and cool off and hence, the famous Obelisk pose. The muscles that flap its wings need to be warm at all times. Coming back to the Obelisk, dragonflies bask on the sun as much as possible when they need the heat. And when they need a little breather from the warmth, they position their bodies in such a way that it makes a little or no direct contact with the sun's rays.
They also do something quite similar to catch the warmth of the setting sun. Same pose, vastly different purposes.
DRAGONFLY LIFE CYCLE
EGG
Female dragonflies can lay hundreds of eggs during their adult life, in batches over a few days or even weeks. Eggs are laid either into plant material (endophytic eggs) or deposited loosely into water ( ecophytic eggs). The former are elongated, but the latter are rounded and laid in a jelly-like substance which confers some protection.
Eggs hatch either within 2-5 weeks depending on the temperature.
NYMPH
Dragonly larvae is also called nymphs or naiads. This immature looks quite different from the adult dragonfly. All dragonfly and damselfly nymphs are aquatic, and remain in the water until they are ready to molt into adulthood. During this aquatic stage, odonate nymphs breath through gills. Damselfly gills are located at the end of the abdomen while the gills of dragonfly larvae are found inside their rectum to respire. When they expel the water, they are propelled forward. Damselfly nymphs swim by undulating their bodies.
Like adult dragonflies the nymphs are predator. Their hunting methods vary. Some species lie and wait for prey, and hide by either burrowing in the mud or resting within the vegetation. Other species hunt actively, sneaking up on prey or even swimming in pursuit of their meals. Odonate nymphs have modified lower lips which they can thrust forward in a split of second to grab a passing tadpole, arthopod or small fish.
MOLT
Unlike other winged insects, such as butterflies, dragonflies do not have a pupal stage but progress to adults through a final larval molt that take place out of water. Triggered by day length and temperature, emergence is synchronized in some species, such as Emperor dragonfly, which emerge in spring but is more extended in the later emerging species.
Final-stage larvae sit in shallow water near the margins of several days, getting ready for their final molt and starting to breathe air. Most species leave the water during the morning but hawkers do so undercover of darkness. Larvae climb up robust emergent vegetation, although some may walk several meters dry land before finding somewhere suitable. After finding a secure support, they redistribute their body fluids. - first to push the thorax, head, legs and wings out of the larva skin. There is then a pause about 30 minutes to allow their legs to harden enough for the next stage, when the abdomen in withdrawn. The wings and the abdomen are expanded and start to harden. This process leaves behind a cast skin, called an exuvia. And last for three hours (in the case of dragonflies).
ADULT DRAGONFLY
Newly-emerged adult dragonflies known as tenerals are a pale green color at first, with only hits of the final adult patterning. Their wings remain very reflective for a couple of days and the flight is weak and fluttery. As the body and wings harden off, they begin hunting food whenever fine weather permits. They spend about a week, depending on the weather, feeding away from the water and gradually acquire adult coloration and sexual maturity.
When mature, adult move back to the water to breed. The males of some species, notably dragonflies are territorial and battle constantly to obtain and defend a suitable length of water's edge. They investigate any potential interloper and specially females, which they will try to seize and mate. The number of adult found in water is determined by the species' territorial behavior. Territorial species are always found in smaller numbers than gregarious species, such as the blue damselflies, which maybe present in hordes.
Mating in dragonflies is unique. The male first transfers sperm from near the tips of abdomen to accessory genitalia under the front. He then grasps a female by the "scruff of her neck" with the anal appendages at the tips of his abdomen: the pair is said to be in tandem. If the mood takes her, the female curls the tip of her abdomen to meet the male's accessory genitalia and sperm is transferred; this position is known as "the wheel" or technically in capola. In some species, such as the chasers, the whole mating process takes only a few seconds; at the other extreme Blue-tailed damselflies take up to six hours.
Cross breeding between different species by species specific combinations of the shapes of the male's anal claspers and the rear of the female's head. Although virtually impossible to see in the field, this can provide conclusive proof of identity of some difficult species (as does wing venation).
Egg-laying occurs soon after mating. Females that lay alone frequently have difficulty avoiding the attentions of male and therefore may choose to lay during poorer weather, even in rain. Adult dragonflies are most active between mid-morning and mid-afterword, when temperatures are highest. In Britain flight is generally restricted to sunny weather, when the flight muscles in the thorax are sufficiently warm. This is especially the case for species that spend most of their time perched. Alternatively, a tactic used by hawkers especially by females (allowing them to lay eggs during cooler weather), is to generate heat in the flight muscles by vibrating their wings. Generally though dragonflies seem to disappear in wet or cool cloudy conditions. In reality, they sit still and well hidden among vegetation, often hanging under leaves in trees.
The life-expectancy of adults is short, typically no more than a week or two,
but expectationaly 6-8 weeks.
10 Facts about Dragonflies
1. Dragonflies are ancient insects.
Long before the dinosaurs walked the Earth, dragonflies took to the air.
If we could transport ourselves back 250 million years, we would immediately recognized the familiar sight of dragonflies flying in pursuit of prey. Griffenflies, the gigantic precursor of our modern dragonflies, took flight in the carboniferous period over 300 million years ago.
2. As nymphs, dragonflies live in the water.
There's a good reason why you see dragonflies and damselflies around ponds and lakes - they're aquatic! Female dragonflies deposit their eggs on the water's surface or in some cases, insert them into an aquatic plants or mosses. Once hatched, the nymphs (or naiad in this case) spends its time hunting other aquatic invertibrates. Larger species will even eat the occasional small fish or tadpole. After molting,9-17 times, the dragonfly will finally be ready for adulthood , and the nymph will crawl out of the water to shed its final nymphal skin.
3. Dragonflies breath through its anus.
A damselflies breathe with gills at the end of its abdomen.
The dragonfly nymph's gills, oddly, are inside its rectum.That's right, its breathes with its butt. The dragonfly nymph will pull water into its anus where gas exchange occurs. When the dragonfly expels the water from its rear, it propels the nymph forward, providing the added benefit of locomotion.
4. Up to 90% of dragonfly adults get eaten.
When the nymph is finally ready for adulthood, it crawls out of the water onto a rock or plant stem and molts one last time. It takes up to an hour for the adult to expand its body. This newly emerged dragonfly, referred as to a teneral adult, is soft-bodied and pale, and highly vulnerable to predators. For the first few days, until its body hardens fully, it is weak flier. Teneral adults are ripe for the picking, and birds and other predators consume a significant number of young dragonflies in the first few days after emergence.
5. Dragonflies have excellent vision.
Relative to other insects, dragonfly vision is extraordinarily good. The head consists almost entirely of two huge compound eyes, which gives a dragonfly nearly 360 degree vision. Each compound eye contains as many as 30,000 lenses or ommatidia. A dragonfly uses about 80% of its brain to process all this visual information. They can see a wider spectrum of colors than humans. This remarkable vision helps them detect the movement of other insects and avoid collisions in flight.
6. Dragonflies are masters of flights.
Dragonflies can move each of their four wings independently. In addition to flapping each wing up and down, they can rotate their wings forward and back on axis. This flexibility enables them to put on an aerial show like no other insect. Dragonflies can move straight up or down, fly backwards, stop and hover, and make hairpin turns at full speed or in a slow motion. A dragonfly can fly forward at a speed of 100 body lengths per second, or up to 30 miles per hour. Scientists at Harvard University used high-speed cameras to study dragonfly flight. They photographed dragonflies taking flight, catching prey, and returning to a perch all within the time span of just 1-1.5 second.
7. Male dragonflies exhibit aggression toward other males.
Competition for females is fierce and male dragonflies will aggressively fend off other suitors. In some species, males will claim and defend a territory against intrusion from other males. Skimmers, clubtails and petaltails scout out prime egg laying locations around the local pond.
Should a competitor fly into his chosen habitat, the depending male will chase him off. Other kinds of dragonflies don't defend specific territories, but will still behave aggressively to other males that cross their flight paths or dare to approach their perches.
8. The male dragonfly has a secondary sex organ.
In nearly all insects, the male sex organs are located at the tip of abdomen. Not so in male dragonflies. His copulatory organ in on the underside of his abdomen, up around the second and the third segments. His sperm, however, is stored in an opening of his ninth abdominal segment. Before mating he has to fold his abdomen and transfer his sperm to his penis.
9. Some dragonflies migrate.
A number of dragonfly species are known to migrate, either singly or in mass. As with other organisms that migrate, dragonflies relocate to follow or find needed resources or in response to environmental changes like cold weather. Green darners , for example, fly south each fall, moving in sizable swarms. They migrate north again in the spring. The globe skimmer is one of several species known to develop in temporary fresh water pools. Forced to follow the rains that replenish their breeding sites, the globe skimmer set a new insect world record when a biologist documented its 11,000 mile trip between India and Africa.
10. Dragonflies are capable of thermoregulation.
Like all insects, dragonflies technically ectotherms. But that doesn't mean they're at the mercy of mother nature to keep them warm or cool. Dragonflies that patrol (fly back and forth, versus that tend to perch) will fire up their wings using a rapid whirring movement to warm up their bodies. Perching dragonflies rely on solar energy for warmth, but position their body skilfully to maximized the surface area exposed to the sun's rays. Some are even use their wings as reflectors, tilting them to direct the solar radiation toward their bodies. Conversely, during hot spells some dragonflies will position their bodies to minimize sun exposure and use their wings to deflect the sun.
3. Dragonflies breath through its anus.
A damselflies breathe with gills at the end of its abdomen.
The dragonfly nymph's gills, oddly, are inside its rectum.That's right, its breathes with its butt. The dragonfly nymph will pull water into its anus where gas exchange occurs. When the dragonfly expels the water from its rear, it propels the nymph forward, providing the added benefit of locomotion.
4. Up to 90% of dragonfly adults get eaten.
When the nymph is finally ready for adulthood, it crawls out of the water onto a rock or plant stem and molts one last time. It takes up to an hour for the adult to expand its body. This newly emerged dragonfly, referred as to a teneral adult, is soft-bodied and pale, and highly vulnerable to predators. For the first few days, until its body hardens fully, it is weak flier. Teneral adults are ripe for the picking, and birds and other predators consume a significant number of young dragonflies in the first few days after emergence.
5. Dragonflies have excellent vision.
Relative to other insects, dragonfly vision is extraordinarily good. The head consists almost entirely of two huge compound eyes, which gives a dragonfly nearly 360 degree vision. Each compound eye contains as many as 30,000 lenses or ommatidia. A dragonfly uses about 80% of its brain to process all this visual information. They can see a wider spectrum of colors than humans. This remarkable vision helps them detect the movement of other insects and avoid collisions in flight.
6. Dragonflies are masters of flights.
Dragonflies can move each of their four wings independently. In addition to flapping each wing up and down, they can rotate their wings forward and back on axis. This flexibility enables them to put on an aerial show like no other insect. Dragonflies can move straight up or down, fly backwards, stop and hover, and make hairpin turns at full speed or in a slow motion. A dragonfly can fly forward at a speed of 100 body lengths per second, or up to 30 miles per hour. Scientists at Harvard University used high-speed cameras to study dragonfly flight. They photographed dragonflies taking flight, catching prey, and returning to a perch all within the time span of just 1-1.5 second.
7. Male dragonflies exhibit aggression toward other males.
Competition for females is fierce and male dragonflies will aggressively fend off other suitors. In some species, males will claim and defend a territory against intrusion from other males. Skimmers, clubtails and petaltails scout out prime egg laying locations around the local pond.
Should a competitor fly into his chosen habitat, the depending male will chase him off. Other kinds of dragonflies don't defend specific territories, but will still behave aggressively to other males that cross their flight paths or dare to approach their perches.
8. The male dragonfly has a secondary sex organ.
In nearly all insects, the male sex organs are located at the tip of abdomen. Not so in male dragonflies. His copulatory organ in on the underside of his abdomen, up around the second and the third segments. His sperm, however, is stored in an opening of his ninth abdominal segment. Before mating he has to fold his abdomen and transfer his sperm to his penis.
9. Some dragonflies migrate.
A number of dragonfly species are known to migrate, either singly or in mass. As with other organisms that migrate, dragonflies relocate to follow or find needed resources or in response to environmental changes like cold weather. Green darners , for example, fly south each fall, moving in sizable swarms. They migrate north again in the spring. The globe skimmer is one of several species known to develop in temporary fresh water pools. Forced to follow the rains that replenish their breeding sites, the globe skimmer set a new insect world record when a biologist documented its 11,000 mile trip between India and Africa.
10. Dragonflies are capable of thermoregulation.
Like all insects, dragonflies technically ectotherms. But that doesn't mean they're at the mercy of mother nature to keep them warm or cool. Dragonflies that patrol (fly back and forth, versus that tend to perch) will fire up their wings using a rapid whirring movement to warm up their bodies. Perching dragonflies rely on solar energy for warmth, but position their body skilfully to maximized the surface area exposed to the sun's rays. Some are even use their wings as reflectors, tilting them to direct the solar radiation toward their bodies. Conversely, during hot spells some dragonflies will position their bodies to minimize sun exposure and use their wings to deflect the sun.
RESOURCES:
http://www.dragonfly-site.com/
https://british-dragonflies.org.uk/content/biology-ecology
https://www.thoughtco.com/fascinating-facts-about-dragonflies-1968249
https://www.thoughtco.com/fascinating-facts-about-dragonflies-1968249
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