ALLIGATORS AND CROCODILES SNAKES AND LIZARDS TURTLES AND TORTOISES

ALLIGATORS AND CROCODILES

Let's start with alligators and crocodiles. Of the reptiles on Earth, the alligators, crocodiles, and others of this type are the largest around. Did you know that some of them get larger than 18 feet long (over 6 meters)? This group of reptiles is called Crocodilia even though they aren't all crocodiles. Some scientists think that they are more closely related to birds than any other reptile. If you're out looking for one, you'll find them near the water in warmer climates. Reptiles don't do well in the cold.

SNAKES AND LIZARDS

Both snakes and lizards are in the order calledSquamata. Snakes are special because they have no legs. You knew that fact. But did you know that snakes don't have ears? They feel vibrations and smell with their tongues. Did you know that snakes can unhook their jaws so that they can swallow prey that is actually wider than they are? Very cool. Don't worry about snakes being slimy. They aren't. They are just very shiny because of their specialized scales.

With so many types of lizards, we don't know where to begin. Lizards have scales just like snakes. They also have legs. They can dig, climb trees, and grab things. It's very handy to be able to grab on to things. Those legs and feet are also placed under the body, so they can walk around without hitting the ground.

TURTLES AND TORTOISES

Turtles and tortoises are the special species that have shells. Some are found in forests, some are in the water, and some are in the deserts. Turtles and tortoises are able to live anywhere that the temperatures are warm enough. They are also able to live a very long time, sometimes over 100 years. Turtles are usually the ones found near water. Tortoises are found on land and dry areas. Scientists group turtles and tortoises together in the order Chelonia.

VERTEBRATE

VERTEBRATE BASICS

Vertebrates are the most advanced organisms on Earth. The traits that make all of the animals in this section special are their spinal cords, vertebrae, and notochords. It's all about having a series of nerves along your back (dorsal side). If you are an organism, you can't just have the nerves sitting there. You need to give those nerves support and protection. That need brings us to the backbones and a rod of cartilage called the notochord.

NOT SO MANY SPECIES

Fifty thousand species might seem like a lot. Compared to the invertebrates, there are not that many species of vertebrates. You might be asking why. One reason is that vertebrates are usually larger than invertebrates. They need more space. Another reason is that, even though they are more advanced, there are many limitations on the environments that are available to them.

Think about it this way. If you are smart mammal, would you rather live near the ocean or in the frozen tundra of the arctic? Many land animals can make that decision and move to more desirable areas for living. Those nicer areas can only support so manyspecies of animals.

THEY'VE GOT THE BRAINS

Vertebrates are smart. Some of them are very smart. We mean you. Most vertebrates have very advanced nervous systems. While a goldfish might not compare to your intelligence, when you compare a goldfish to a sea anemone, a goldfish is like Einstein. Octopi are probably the smartest invertebrates and may equal or be smarter than some vertebrates. Octopi are the exception in the invertebrate category.

More cool traits about vertebrates are that they have muscles and skeletons. While the materials may vary, muscles allow vertebrates to move around very efficiently and perform complex moves. That ability to move and the intelligence to go with it gives vertebrates such as reptiles and birds an advantage in the natural world.

INSECTS ARE EVERYWHERE

We've talked about arthropods with spiders and crustaceans, but the biggest category of arthropods is the uniramians with all insect species. There are about 26 orders in the Class Insecta and you will find species everywhere. There may be tiny little fleas and there may be monster mosquitoes in the jungle. There may be beetles digging in burrows under the ground or dragonflies zipping around a pond. Insects are everywhere. Even in a simple backyard garden you might find twenty species that include butterflies, aphids, bees, flies, beetles, and grasshoppers.

BASIC STRUCTURE STUFF

With such a variety, where do you start? Can a class with so many species have any similarities? Yes. They are hexapods. That means they usually have six legs. While a deer might have four and a spider might have eight, insects usually have six legs. They have exoskeletons made of chitin. They usually have compound eyes. Compound eyes have a series of facets, each one acts like a little eye with its own parts. A fly's eye is a classic example of a compound eye. They also have complete digestive tracts. While it might not seem like a big deal to you, having a mouth and an anus is a big advantage for an organism.

That's where our list of similarities will end. The fun stuff is in the specialized structures you will find on insects. Insects were the first organisms to fly. Several species developed wings of transparent chitin and flight muscles that contract quickly. Flying was a big advantage when species were developing. A whole niche was open for new species. Many insects have also developed toxins. Bees are an easy example of insects that can sting and poison you. Speaking of bees, many insects have developed different compounds beyond poisons. Insects can make wax, silk, andhoney. Some insects such as butterflies have antennae. The list goes on.

METAMORPHOSIS

Insects go through a process of metamorphosis. It's not the same for all species. Grasshoppers go through incomplete metamorphosis that happens when it loses its exoskeleton as it grows. It is incomplete because a baby grasshopper looks basically like an adult grasshopper, just smaller. Other insects go through a complete metamorphosis. These insects include butterflies and have a complete change in body structure. Butterflies start as eggs and hatch into caterpillars. When the time comes, those caterpillars develop a protective case and transform into a butterfly. The beginning looked nothing like the end.

HUMANS AND INSECTS

We love them and we hate them. Mosquitoes spread diseases across the world. Since they take in blood, small viruses and microorganisms can hitch rides and move from one organism to another. For every mosquito there is a honey bee that helps us pollinate crops and provides us with some types of food. While the bees might sting when they feel threatened, they make modern farming possible.

Back to the negative. Insects can destroy our crops. Locust swarms can eat entire wheat fields or fruit flies lay eggs in our fruit. It's a constant battle to find a natural way to control insects and still allow them to survive. The thing you need to remember is that the insects don't want to hurt us or compete with us. They are just out there trying to survive. They look for opportunities and take advantage of them. An opportunity for an insect might have ladybugs eating aphids from our plants. Another opportunity might have termites eating the wood in your house. They just go where the food is.

LOOKING AT ARTHROPOD STRUCTURE&METAMORPHOSIS

LOOKING AT ARTHROPOD STRUCTURE So what makes an arthropod? Why is it different from a mammal? Does an arthropod have a skeleton? Yes, but it's on the outside and called an exoskeleton. You might be wondering how an arthropod can get bigger if it has a hard outer skeleton. Doesn't it outgrow the shell? Yes. It has to shake off the shell and let a new one grow every now and then. When an arthropod loses one exoskeleton to grow bigger, it's called molting. Do arthropods have legs to move? Yes again! They have special legs that are jointed. They usually have several legs, more that the four that mammals have. Do they think? That's a tough one. They have advanced nervous systems. They even have groups of neurons that think and help the organism hunt, move around, and find a mate. Do they sit back and think about watching television? Probably not. Can they learn? Yes. Not a lot, but they can learn new behaviors. It helps them adapt to new situations. METAMORPHOSIS We have one more big idea to introduce about arthropod development.Metamorphosis is a process where you change your body shape as you grow. In insects, it can be very special. There are even different kinds of metamorphosis. COMPLETE AND GRADUAL You may have learned about caterpillars changing into butterflies. That is a complete metamorphosis. Another complete metamorphosis happens when maggots turn into flies. Complete metamorphosis means that the entire body shape has changed (wormlike into insect with wings). The other type of metamorphosis is calledgradual metamorphosis. Grasshoppers are a good example of a gradual one. They start off as small odd-shaped grasshoppers with no wings. As time passes, they molt their exoskeletons and grow wings. It's not a big change like a butterfly.

ANEMONE AND CORALS

ANEMONE AND CORALS - THE CNIDARIANS

We'll start by explaining that anemone, coral, and jellyfish are all related. We broke them up into two different sections because of their body types. They are all from thePhylum Cnidaria. Comb jellies are a side step away from jellyfish. They are in the Phylum Ctenophora. They look similar, but are different in some important ways.

ANEMONE

Specifically, anemones are considered the cnidarians that look like flowers. They have a central body and dozens of tentacles waving in the water, waiting for prey to pass by. You can find them alone or in groups. If you ever go to tide pools, you will see them all over the rocks. You will find anemone wherever you find a lot of fish and healthy water.

CORALS

Corals are different from anemone because they have a skeleton of sorts. Anemones are squishy and basically filled with water. Corals create a hard skeleton of calcium carbonate. You might see that skeleton for sale in stores. When you find living coral and look very closely, you will see thousands of living cells waving about in the water. We should probably mention, although obvious, that coral do not go anywhere. Once they settle down, that's it. You might find coral alone or thousands of them together forming entire reefs like the Great Barrier Reef near Australia.

NVERTEBRATES -

NVERTEBRATES -
ONE OF TWO MAJOR ANIMAL GROUPINGS

There are two basic groups of higher animals. They are vertebrates and invertebrates. While both have advanced through the processes of evolution, there is one fundamental difference. Invertebrates do not have backbones. Both groups are in the Kingdom Animalia, but their bodies are organized differently. What makes invertebrates different? All invertebrates share common traits. At the bottom of the invertebrate world are the sponges. Sometimes they don't fit in but they are still part of the group. Here's the nice and neat little list.

(1) They are multicellular. It's more than being a colony of individual cells. The cells are working together for the survival of the organism. All of the cells have specific duties and responsibilities.

(2) No backbone. We already talked about this one. That's the whole definition of invertebrate, no vertebrae.

(3) No cell walls. When we talked about plants, we always mentioned cell walls. Invertebrates don't have them. Remember that even if none of them look like animals, they are. Being an animal means you have no cell wall.

(4) Here are a few that have the qualifier "most" attached. That means not all of them have the trait, but most do. Most of them have tissues (not sponges) that are specific organizations of cells. Most of them reproduce sexually (not asexually). That means twogametes combine to form a new organism. Those gametes come from separate organisms (male and female).

Most invertebrates can move. Even sponges move when they are very young and very small. Once they settle down they don't move anymore. Other invertebrates likelobsters and insects move around their whole lives. Most invertebrates are organized in a way called symmetrical. Symmetrical organization means when you can draw a line down the middle of the organism and the two sides look like mirror images. Draw a line down the middle of yourself and one side looks like the other side. If you draw a line down the middle of an octopus you would find two sides with equal parts. Remember we said most? Sponges and some coral are not symmetrical.

(5) Invertebrates can't make their own food. Scientists use the word heterotrophic. Heterotrophs feed off other things to get their energy. Plants are autotrophic. They make their own food. Being heterotrophic is one of the main characteristics of being an animal. We eat things, whether it is plants or other animals. That's just the way the world works.

FIRST PLANTS WITH FLOWERS

ANGIOSPERMS - FIRST PLANTS WITH FLOWERS

We asked it before. What would give you an advantage if you were a plant? You have a vascular system to transport nutrients. You have seeds for reproduction that allow your babies to spread out in new areas. What next? Flowers! Flowers are the most recent evolutionary advantage for plants.

LOOKING GOOD FOR THE BIRDS AND BUGS

When we talked about gymnosperms, we spoke of seeds. That was a big advantage. The angiosperms took it one step further. They not only have seeds, but they also have flowers. What kind of an advantage is that? Many angiosperm species use wind for pollination the way that gymnosperms do. What if you didn't need to rely on the wind to spread your pollen around anymore? What if another creature could do it for you? Maybe an insect? Sounds like a new advantage.

Those specialized flowers are able to attract organisms to help pollinate and distribute seeds. Another cool advantage is the fruit/seed packaging. Would you rather eat a pine cone or an apple? A lot of animals would go for the apple. When they do, they are able to spread the seeds across wide areas after the animal poops out the seeds.

SOME WITH ONE COTYLEDON

There are two kinds of seeds in the angiosperms,monocots and dicots. Monocot is short for monocotyledon. A cotyledon is the seed leaf. When you are a monocot, your seed only has one package of food. "Mono" means one or a single cotyledon. Monocots are made up of simple flowering plants like grasses, corn, palm trees, and lilies. Two of the characteristics of monocots are that their flowers have petals in numbers of three and their leaves are made of long strands. Think of the leaves of grass or a palm frond.

AND SOME WITH TWO

The other kind of plant in the flowering plant world is called a dicot. Dicot is short for dicotyledon. "Di" means two or a double cotyledon. These plants have seeds that have two cotyledons, two seed leaves of food for the embryo. Most of the flowers you see every day are dicots. They have flowers with petals in numbers of four and five. They also have really complex leaves with veins all over, not long like monocots. Some examples of dicots are roses, sunflowers, cacti, apple, and cherry plants.

FIRST PLANTS WITH SEEDS

GYMNOSPERMS - FIRST PLANTS WITH SEEDS

So you've got a vascular system. What comes next? Seeds. Seeds let you send your offspring out into the world. Seeds provide a protective coat so that the embryo plant can develop when it finds a nice piece of soil. But remember this: gymnosperms have not developed the ability to make flowers. Flowers are an evolutionary advancement after seeds. So if you have a vascular system, seeds, and no flowers, what are you? A gymnosperm!

Seeds are a protective structure that lets a plant embryo survive for long periods of time before it germinates. Seeds have food sources pre-packaged for plant embryos to provide for an embryo's needs in early growth. Seeds let plants spread their embryos over large areas. Some are even so lightweight that they are carried across the planet by strong winds. Seeds are an advantage if you want to be a plant that can grow anywhere. Seeds are da bom'!

CYCADS IN THE TROPICS

Looking like a fern. Looking like a palm tree. It's actually neither! It's a cycad. These are another favorite of landscape designers. These are sturdy little plants that can survive in harsh conditions. You won't find them in cold areas like the conifers. Cycadsneed warmer weather to survive. They have cone-like structures for reproduction. Instead of being on branches, their cones are in the center of the plant and can get really large. They also have big waxy fronds, and when it's time to reproduce, the female plants have a great fruit that grows in the middle of their stem.

CONIFERS IN THE FORESTS

Pine, cedar, redwood, and spruce. Sounds like we're at a hardware store buying lumber. Not so. We are listing off a bunch of trees that are called conifers. If you've ever gone skiing or to northern latitudes you have seen loads of conifers. The conifers most people think of are pine trees. Every year millions of trees are grown for Christmas and they are all conifers. They usually have needles and cones (thus the name CONifer).

They are also evergreens: even in cold winter months they are able to keep their needles. That ability is one reason they do so well in northern latitudes. The ever-present needles allow conifers to take advantage of the Sun whenever it is around. They are also some of the tallest plants in the world. They are able to get very tall and strong because of heavy-duty xylem that hardens and makes them sturdy. That sturdiness is why these kinds of trees make good lumber - hard and strong wood.

GINKGOES ON YOUR STREET

Not every plant made it to the modern day. Fossil evidence shows what plants used to be alive in other geological eras. The Ginkgo is one of the ones that made it. Some people call it a "Maidenhair Tree". It's the last one of its kind. It has needles that have combined to form very sturdy leaf-like structures. You need to remember they are not like leaves in the traditional sense. You've probably seen these all over. Landscape designers love to use them because they look very nice and are very resistant to pollution. They are great for cities. Being able to resist insects and disease has let this species survive beyond all of its close relatives.

A GENERAL PLANT STRUCTURE

We're going to look at plant structure in this section. The plants we discuss will be vascular plants that have systems of tubes (xylem and phloem) for the transport of nutrients and water. Remember that there is a wide variety of plants on Earth and even a whole group that doesn't havevascular systems. Mosses and liverworts may still have photosynthesis, but they do not have that 'classic' plant structure. Then you will find species such as cacti that don't have leaves. They conductphotosynthesis in their stems. Anyway, just remember that there are many other possibilities in the plant kingdom.

ALIKE BUT DIFFERENT

We just told you about the many exceptions to the basic plant structure, so let's look at some similarities. An easy similarity is on a cellular level. Plants conduct photosynthesis. This process of converting the Sun's energy into molecular energy happens in chloroplasts with the help of chlorophyll molecules and a variety of enzymes. Vascular plants share a similar set of structures called roots, stems, and leaves. Many plants have specialized versions, but the basics are there. One specialization might be the petals of a flower. Those flower petals are specialized leaves that surround the reproductive structures of the plant.

THE ROOTS BELOW GROUND

We'll start at the bottom with the roots. These structures are designed to pull water and minerals from whatever material the plant sits on. For water plants, the roots may be in the water. For traditional trees, the roots go deep into the soil. There are even plants called epiphytes that live in trees and their root system clings to branches. Humans often capitalize on the roots of plants for food. Carrots are just one big orange root.

Root systems also provide support for plants in the form of an anchor in the soil. If the wind blows hard, those roots keep the plant from falling over. Some plant species have roots above ground that provide support for the entire plant. Roots are further broken down into the primary root and lateral roots that each has apical meristem at their tips. Root hairs are also a common structure on roots. They make the roots look fuzzy and help in the absorption of water and nutrients.

SHOOTS ABOVE GROUND

Sure we said that there are some roots above the surface, but the majority of the plant you see is made up of stems and leaves. Think about a tree. The stems are the trunks and branches. Leaves are self-explanatory. Stems are all about transporting food and water and acting as support structures. Leaves are all about photosynthesis, creating food molecules and absorbing carbon dioxide for the plant. These parts are connected by the vascular system of xylem and phloem that spreads through the entire plant.

The tip (terminal bud) of the main stem has a specialized structure that is the source of new growth for plants. You will find the apical meristem that develops into young leaves (primodium). There are other points of growth at each node where leaves and branches develop on the stems. Those branching points are home to axillary budsthat can also develop into new branches.

PHOTOSYNTHESIS -

PHOTOSYNTHESIS -
PART I: THE SUN AND LIGHT

Not all of the light from the Sun makes it to the surface of the Earth. Even the light that does make it here is reflected and spread out. The little light that does make it here is enough for the plants of the world to survive and go through the process of photosynthesis. Light is actually energy, electromagnetic energy to be exact. When that energy gets to a green plant, all sorts of reactions can take place to store energy in the form of sugar molecules.

Remember we said that not all the energy from the Sun makes it to plants? Even when light gets to a plant, the plant doesn't use all of it. It actually uses only certain colors to make photosynthesis happen. Plants mostly absorb red and blue wavelengths. When you see a color, it is actually a color that the object does NOT absorb. In the case of green plants, they do not absorb light from the green range.

PART II: THE CHLOROPLAST

We already spoke about the structure of chloroplasts in the cells tutorials. We want to reinforce that photosynthesis happens in the chloroplast. Within this cell organelle is the chlorophyll that captures the light from the Sun. We'll talk about it in a bit, but the chloroplasts are working night and day with different jobs. The molecules are moved and converted in the area called the stroma.

PART III: THE MOLECULES

Chlorophyll is the magic compound that can grab that sunlight and start the whole process. Chlorophyll is actually quite a varied compound. There are four (4) types: a, b, c, and d. Chlorophyll can also be found in many microorganisms and even some prokaryotic cells. However, as far as plants are concerned, the chlorophyll is found in the chloroplasts. The other big molecules are water (H₂O), carbon dioxide (CO₂), oxygen (O₂) and glucose (C₆H₁₂O₆). Carbon dioxide and water combine with light to create oxygen and glucose. That glucose is used in various forms by every creature on the planet. Animal cells require oxygen to survive. Animal cells need an aerobic environment (one with oxygen).

PART IV: LIGHT AND DARK REACTIONS

The whole process doesn't happen all at one time. The process of photosynthesis is divided into two main parts. The first part is called the light dependent reaction. This reaction happens when the light energy is captured and pushed into a chemical called ATP. The second part of the process happens when the ATP is used to make glucose (the Calvin Cycle). That second part is called the light independent reaction.