Phylum Arthropoda

informal presentation about phylum arthropoda

1. 1 “To a good approximation, all species are insects.” -Robert May

2. 3 The Most Successful Animals Princess Mae Mariscal Cedrick Modelo Jinky Mutuc

3. Chances are that you are interacting with arthropods on a daily basis — in your garden, in a nearby stream, in your home, on your dinner table, and perhaps even on your pet! Arthropods abound! Introducing the Arthropods All of the animals pictured here (and many more!) are arthropods. In fact, more than 83% of all described animal species are arthropods. In this investigation, you will delve into the evolutionary history of arthropods to find out how they have evolved over time. You will learn what traits arthropods inherited from their common ancestor, how arthropods got their start over 500 million years ago, and how their lineage has diversified in some ways and been constrained in others . But first, let’s find out what arthropods are up to today. In the next few pages, you’ll get a taste of the enormous variety that arthropods have evolved. Arthropods are found all over the world and make their livings in all sorts of ways.

4. Let's get an idea of just how dominant arthropods are, by looking at how many of them there are. About  a septillion (1,000,000,000,000,000,000) insects  are alive at any time. That's about 160 million insects for each person on Earth! At any moment, there are about  1,000,000,000,000,000 ants  alive on the planet. If each ant were half a centimeter long, they would form a chain long enough to circle the Earth 125,000 times! Tiny crustaceans called copepods , less than a centimeter long, are the most abundant animals in the ocean. There are so many of them, that they outweigh all the whales on Earth! 5 Sheer Numbers 75% of all known species

5. Habitat and Distribution Throughout their evolution, arthropods have invaded new geographic areas and habitats. Wingless fly Gammarus Himalayan Jumping Spider Yeti Crab June Beetle Specter Stick Insect

6. 7 Arthropods: A success story Almost any way you look at them, arthropods are successful: They have been around for more than 500 million years and are still evolving. They live on Earth in overwhelming numbers. They have come in all shapes and sizes. They have evolved to fill a variety of ecological niches — from tiny internal parasite to giant bird-eating predator. About 1,000,000,000,000,000,000

7. 8 What is an Arthropod? We're going to take a closer look at this amazing group of animals called arthropods . You are familiar with a wide variety of arthropods from seeing them in your daily life. Have you thought about what they all have in common? Arthropods are a lot more than just delicious feasts and disgusting pests. Before we go too far, we need to figure out exactly what an arthropod is. In this section, we will explore these key questions: What is an arthropod? Why do all arthropods share certain key characteristics ? OK. Let’s dive right in!

8. 9 Inherited characteristics Bilateral (left/right) symmetry Segmented body Hard Exoskeleton Jointed legs Many pair of limbs

9. Bilateral symmetry One character inherited by all arthropods is bilateral symmetry . Many animals have a body form that is symmetrical, meaning that it could be divided into matching halves by drawing a line down the center. In this respect, arthropods are built like humans are; the right half of an arthropod is a mirror image of its left half — this is called bilateral symmetry ( bi = two, latus = side). 10 Inherited characteristics cont’d

10. 11 Inherited characteristics cont’d Segmented body Another character inherited by all arthropods is a body divided into segments that are often grouped into larger functional units. At some point in their lives, all arthropods have bodies that are internally and externally segmented. These segments piggyback on one another, like a series of cars in a train. Each body segment tends to repeat the same suite of structures (for example, a pair of legs, a set of breathing organs, and a set of nerves), often with slight variations down the length of the animal. Usually, sets of segments are grouped into a larger unit, such as the abdomen.

11. 12 Inherited characteristics cont’d Hard exoskeleton We've seen that arthropods all have bilateral symmetry and segmented bodies. Another character inherited by all arthropods is a hard exoskeleton . The bodies of arthropods are supported, not by internal bones, but by a hardened exoskeleton made of  chitin , a substance produced by many non-arthropods as well. In arthropods, the nonliving exoskeleton is like a form-fitting suit of armor. It is produced by the "skin" and then hardens into a protective outer- covering. This exoskeleton is handy in some ways (it provides protection and prevents water loss), but is limiting in others. In order to grow, all arthropods must shed the exoskeleton and produce a new, larger one.

12. 13 Inherited characteristics cont’d Jointed legs We've seen that arthropods all have bilateral symmetry, segmented bodies, and hard exoskeletons. Another character inherited by all arthropods is jointed legs . Having a hard exoskeleton introduces a problem for arthropods: flexibility . How can an animal with a rigid body covering move its legs? Evolution solved this problem with joints. All arthropods ( arthro  = joint,  pod  = foot) have jointed limbs . In most of the leg, the exoskeleton is hard, but at the joints it is softer and bendable, allowing movement in the same way that a suit of armor does. The limb can be controlled by contracting muscles connected to the exoskeleton on both sides of the joint.

13. 14 Inherited characteristics cont’d Many pair of legs We've seen that arthropods all have bilateral symmetry, segmented bodies, hard exoskeletons and jointed legs. Another character inherited by all arthropods is many pairs of limbs . The ancestral arthropod had many body segments with one pair of limbs on each segment. All arthropods inherited multiple limbs from that ancestor . However, in many arthropods, some limbs have even been lost completely as they evolved to be smaller and smaller, while others have evolved into new shapes. Crayfish, for example, have limbs specialized for different functions.

14. 15 Major branches of the arthropod tree Modern arthropods include insects, spiders, centipedes, shrimp, and crayfish. All arthropods are the descendents of a single common ancestor. Just as you and your biological cousins can trace your ancestry back to a common set of grandparents, all arthropods can trace their ancestry back to a common arthropod ancestor. Any species descended from that ancestor is an arthropod. And any species not descended from that ancestor is not an arthropod.

15. tri - “three” +  lobos - “lobe ” + morphi- “ shape” “three-lobe shaped” Trilobitomorpha 16

16. 17 Trilobites Among famous groups of extinct organisms , trilobites probably rank second only to the  dinosaurs  in fame. Their fossils are instantly recognizable and often strikingly beautiful. In fact, prehistoric people liked them as much as we do. At Arcy- sur -Cure in France, a 15,000-year- old human settlement, one of the artifacts found by archeologists was a trilobite that had been drilled to be worn as an amulet. Trilobites  are the most diverse group of extinct animals preserved in the fossil record.  Ten orders of trilobites are recognized, into which 20,000+ species are placed. Although the last few trilobites went extinct about 245 million years ago, they are one of the best-known and most-studied groups of fossil  arthropods.

17. Arakhnē - “spider” “the spiders” Arachnida 18

18. 19 Arachnids The land-based arachnids   comprise over 98% of living chelicerate species and display a number of marked adaptions to terrestrial existence. The Arachnida include the terrestrial  chelicerates that everyone is familiar with, and that nearly everyone would rather not be too familiar with: spiders ( Araneae ), ticks and mites ( Acari ), and scorpions ( Scorpiones ).

19. Crustacea 20 crūstaceus - “crust ” “crusty-shelled”

20. Crustaceans Crustaceans are a diverse group of arthropods that include lobsters, crayfish, crabs, prawns, shrimp, barnacles, and pill bugs. There are several key characteristics used to identify crustaceans, including a segmented body with an exoskeleton, branched limbs, two pairs of antennae, numerous pairs of appendages on the body for feeding, locomotion and sexual reproduction, and respiration using gills.  There are around 42,000 species of crustaceans, and most of them are marine. Unlike most other arthropods, there are few species of crustaceans found on land or in freshwater.

21. Mūrias - “ten-thousand” + poda - “foot” “ten-thousand footed” Myriapoda

22. Myriapoda The myriapods are centipedes and millipedes , and some small relatives. Centipedes and millipedes look similar to each other; they both look a little like worms with lots of legs . Actually they are arthropods, they have a tough exoskeleton and jointed legs, and they are related to insects and crustaceans. Like insects, myriapods have one pair of antennae, but they have many more legs than insects do. All myriapods have more than 20 legs , and all the other arthropods have fewer legs than that (most have only 6 or 8 legs).

23. hexa - “ six ” + poda “ foot ” “ six-legged ” Hexapoda

24. 6 6 legs Hexapoda Insects don't have spines; they are  invertebrates . Insects have segmented bodies. Their bodies are divided three sections - the head , the thorax , and the abdomen . The head has antennae and a pair of compound eyes . Insects have six legs, one pair on each of its three segments . Some insects also have wings . Insects also have an  exoskeleton . The exoskeleton is an outside covering that protects the insect's internal organs. There are over 800,000 species of insects - more than all the other animal groups combined! Insects can be found in a wide variety of environments all over the world!

25. Facts About Arthropods FACT: Arthropods are a highly successful group of animals—they account for over three quarters of all currently known living and fossil organisms . Of all animal groups, arthropods are the most diverse and their diversity is due in no small part to the diversity of one subgroup , the insects. Scientists approximate that there may be as many as 30 million species of insects alive today. To date, over one million have been identified. The success of arthropods has been attributed to their versatile exoskeleton, the process of metamorphosis , and their metameric body structure . FACT : Ancestral arthropods were the first land animals . The oldest known animal to have lived on land is the arthropod Pneumodesmus newmani . Fossil evidence of this species consists of a single specimen that was discovered in 2004 in Scotland. Pneumodesmus newmani is classified as a millipede and is thought to have lived 428 million years ago, during the Late Silurian Period .

26. Facts About Arthropods cont'd FACT: During their life cycle, arthropods undergo a transformation called metamorphosis. Metamorphosis is a biological process that involves a radical transformation of body form and physiology. The immature form of an organism, called a larva, undergoes metamorphosis to become an adult. Since the larva and adult forms differ greatly in the way they live and what they eat, metamorphosis enables organisms to reduce competition for resources that otherwise would occur between the immature and adult forms.

27. Thank you for listening, Prepare for the activity.