Phylum Arthropoda Presentation PDF

Phylum Arthropoda  Arthropods are segmented coelomates that have an exoskeleton and jointed appendages In terms of species diversity, distribution, and sheer numbers, arthropods regarded as most successful animal phylum Diversity and success of arthropods - largely due to three f...

Phylum Arthropoda  Arthropods are segmented coelomates that have an exoskeleton and jointed appendages In terms of species diversity, distribution, and sheer numbers, arthropods regarded as most successful animal phylum Diversity and success of arthropods - largely due to three features: 1. Body segmentation (modified metamerism) 2. Hard exoskeleton 3. Jointed appendages Groups of segments and their appendages have become specialized for a variety of functions besides movement, permitting efficient division of labor among regions.  Arthropod s - segmented like annelids Arthropod bodies ◻ segments often fuse into three tagmata (anatomical areas) in adult stage Head – contains segments with feeding and sensory activities Thorax – contains segments with locomotor activities Abdomen –contains segments with locomotor and/or reproductive activities ◻ Some arthropods contain head and thoracic segments fused- cephalothorax Segmentation in insects.  Arthropod s by cuticle, an exoskeleton made Body - completely covered of protein and chitin Exoskeleton is strong, protects animal and provides points of attachment for muscles that move appendages Exoskeleton  thick and inflexible in some regions, such as crab claws  thin and flexible in others, such as joints  Arthropod s In order to grow, an arthropod must molt its old exoskeleton and secrete a larger one, a process called ecdysis that leaves animal temporarily vulnerable to predators and other dangers Exoskeleton’s relative impermeability to water helps prevent desiccation and provides support on land Arthropods moved to land after colonization of land by plants and fungi  Arthropod s Open circulatory system in which fluid called hemolymph is propelled by a heart through short arteries into sinuses (the hemocoel) surrounding tissues and organs. Hemolymph returns to heart through valved pores. Hemocoel is not a coelom; the true coelom is much reduced in most arthropods. Well-developed sense organs, including eyes for vision, olfactory receptors for smell, and antennae for touch and smell. Most sense organs located at anterior end of animal, which shows extensive cephalization.  Arthropod s A variety of organs specialized for gas exchange have evolved in arthropods Most aquatic species - have gills with thin, feathery extensions that have an extensive surface area in contact with water Terrestrial arthropods - generally have internal surfaces specialized for gas exchange. Ex: insects - have tracheal systems, branched air ducts leading into interior from pores in cuticle  Representatives of Phylum Arthropoda ◻ Subphylum Chelicerata (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders, i.e. Limulus -horseshoe crab, Argiope – the garden spider)- Contain one pair of chelicerae, one pair of pedipalps. Antennae and mandibles are absent. ◻ Subphylum Crustacea (crabs, lobsters, shrimps, barnacles, and many others, i.e. Cambarus- the crayfish). Primarily found in aquatic environments. Contain two pairs of antennae, one pair of mandibles. ◻ Class Insecta (insects, i.e. Romalea- the grasshopper). Found in terrestrial environments. Contain one pair of antennae and one pair of mandibles.  Subphylum Chelicerata Named for clawlike feeding appendages called chelicerae which serve as pincers or fangs. In their cephalothorax they contain one pair of chelicerae (anterior most appendage). This is followed by one pair of pedipalps (in the middle) and 4 pairs of walking legs (posterior end). They lack antennae and mandibles. Bodies - divided into two tagmata (specialized grouping of arthropod body segments) 1. Cephalothorax – which has locomotor, sensory, and feeding appendages- at anterior end 2. Abdomen – which has visceral functions- at posterior end  Chelicerata Lack sensory antennae, and most have simple eyes (eyes with a single lens). Lack mandibles Most marine chelicerata are extinct, but some species survive today, including horseshoe crabs Majority of living chelicerata are arachnids, a group that includes scorpions, spiders, ticks, and mites We will examine a representative of subphylum chelicerata: ◻ Limulus- horseshoe crab  Subphylum Crustacea Mostly marine, some freshwater, a few terrestrial Most free-living, a few parasitic Bodies consist of two or three tagmata ◻ When two tagmata, cephalothorax is covered by a carapace and contains appendages used in sensing, moving and feeding. ◻ Abdomen - has visceral functions and contains appendages used in moving Example: Crayfish Paired, jointed appendages show specialization  Subphylum Crustacea Last division of crustacean body– Telson (shown in orange in image) - not considered a true segment Pair of appendages next to telson - called uropods Examples: Copepods, Crayfish, Barnacles, Lobsters, Shrimps, Crabs, Isopods (pillbugs), Cambarus – crayfish We will look at crayfish, a freshwater crustacean- Cambarus as a representative  Subphylum Crustacea Distinctions: ◻ All crustaceans have two pairs of antennae, two pairs of maxillae, a pair of mandibles, and a pair of compound eyes commonly found on stalks ◻ Respiratory system - consists of gills http://www.earthlife.net/insects/glossary.html#13 cas.bellarmine.edu/tietjen/PPT/Arthropoda.ppt  (a) Biramous (b) Uniramous “Two-branched” “One-branched” http://accessscience.com/popup.aspx?figID=401700FG0020&id=401700&name=figure http://www.earthlife.net/inverts/crustacea.html http://www.google.com/imgres?um=1&hl=en&client=firefox-a&hs=7oO&sa=N&rls=org.mozilla:en-US:official&biw=1440&bih=698&tbm=isch&tbnid=CE4rrp7aw4d_vM:&imgrefurl=http://en.wikipedia.org/wiki/ Arthropod_leg&docid=o3BgN434Tp4BIM&imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/3/30/InsectLeg.png/220px- InsectLeg.png&w=220&h=321&ei=4rA6T9WxCKrz0gHmhaDTCw&zoom=1&iact=rc&dur=391&sig=102740219842331340371&page=2&tbnh=167&tbnw=113&start=18&ndsp=26&ved=1t:429,r:17,s:18&tx=64&ty=66 C:\Users\eribeiro\Desktop\Eugenia\Teaching not yet transfered\Spring 2011 Bio II\spring 2011 blackboard\Intro Bio II spring 2011 blackboard\Crayfish appendages.gif  Crayfish Appendages Starting from the posterior end: Uropods- 1 pair located in abdomen- they are biramous. In conjunction with telson, they make up tail fan which helps with moving and “fanning” the eggs and young Swimmerets- 5 pairs located in abdomen-they are biramous. Used for swimming.  In males – pair at anterior end is modified for copulation  In females – swimmerets can be used to hold fertilized eggs  Crayfish Appendages Walking legs- 5 pairs located in thorax- they are uniramous- All except last pair contain gills. Pair of walking legs closest to anterior end contain larger pincers -chelae and are known as chelipeds. Second and third pairs also contain small pincers at their tips Maxillipeds- 3 pairs located in thorax- they are biramous. Function in handling food and chemosensation. Second and third maxillipeds have gills attached Maxillae- 2 pairs located in head- they are biramous. Function in food handling. Second pair contains gill bailers which play a role in creating water currents through gill chambers  Crayfish Appendages (cont’d) Mandibles- 1 pair located in head- they are uniramous. Play a role in tearing up food for swallowing Antennae- 1 pair located in head- they are biramous. Play a role in chemosensation. At base of antennae, there is a nephridiopore which empties green gland Antennules- 1 pair located in head- they are biramous. They function in chemosensation and equilibrium  Crayfish head and thorax fused  Crayfish Internal Anatomy Gills (1), digestive gland (2), green gland (3), compound eye (4) and cheliped (5).  Insect Diversity The only winged invertebrates More than 800,000 known species Most successful species are small in size and have a great reproductive capacity Example: Romalea (grasshopper)  Class Insecta Found in terrestrial habitats Body Plan - divided into three tagmata 1. Head - containing appendages used in sensing and feeding 2. Thorax - containing appendages used in moving 3. Abdomen - containing no appendages and having visceral functions  Open Circulatory System in Insects Hemolymph – blood- like fluid which transports electrolytes, nutrients, and wastes Dorsal Heart Sinuses http://www.biologyjunction.com/grasshopper_dissection.htm  Insect Body Plan One pair of antennae (which sets them apart from crustaceans, which have two pairs) and one pair of mandibles Thorax - usually has three pairs of walking legs and one or two pairs of wings Abdomen - contains most internal organs and specialized structure for reproduction Three-part gut They have unbranched appendages We will look at grasshopper (Romalea) as a representative of Class Insecta  New features found in Insects Respiration - system of internal tubes- tracheae- and sacs delivering oxygen directly to cells. Air is taken in through openings called spiracles. Excretion - via Malpighian tubules which are blind- ending, tube-like appendages of intestine that open at border between mid- and hindgut. As hemolymph circulates in hemocoel near these Malpighian tubules, uric acid is actively transported and discharged into hindgut, from where the excretory products are passed with feces. Locomotion – wings for flight; legs for walking http://parasitology.informatik.uni-wuerzburg.de/login/n/h/0715.html  Insect Metamorphosis Metamorphosis - biological process by which an animal develops, grows and changes form (from an immature form to a mature form) to give rise to adult There are some insects that ◻ Show no metamorphosis ◻ Show gradual or incomplete metamorphosis ◻ Show complete metamorphosis Dr. Iwantsch, Fordham University  Growth and Types of molting Insect Development egg young adult Different stages exploit different resources at different times Incomplete metamorphosis Insects molt in order to grow In incomplete metamorphosis - insect young look like egg nymphs adult adults, they simply have Complete different body proportions. metamorphosis Whereas in complete metamorphosis - larval stages specialized for eating egg larva pupa adult e  Gradual (Incomplete) Metamorphosis Incomplete metamorphosis has 3 stages: 1. Egg - A female insect lays eggs 2. Nymph or naiad – Eggs hatch into nymphs. Nymphs look like small adults, but usually lack wings and have undeveloped reproductive systems. Insect nymphs eat same food as adult. Nymphs shed or molt their exoskeletons and replace them with larger ones several times as they grow. Most nymphs molt 4-8 times. As they molt both their reproductive organs as well as their wings become progressively more mature. 3. Adult – Insects stop molting when reach adult size. By this time, they have also grown wings. http://www.uen.org/utahlink/activities/view_activity.cgi?activity_id=2024  Complete Metamorphosis Complete metamorphosis has 4 phases: 1. Egg - A female insect lays eggs 2. Larva - hatch from eggs. Do not look like adult insects. Usually have a worm-like shape. Caterpillars, maggots, and grubs are all just the larval stages of insects. Larvae molt their exoskeleton several times and they grow slightly larger. 3. Pupa - Larvae make cocoons around themselves. Larvae don't eat while they're inside cocoons. Bodies undergo an extreme reorganization (both internally as well as externally) and develop into mature adult shape with wings, legs, internal organs, etc. Change takes anywhere from 4 days to many months. 4. Adult – Inside cocoon, the pupa changes into an adult. After a period of time, adult breaks out (molts) of cocoon (pupal exoskeleton) http://www.uen.org/utahlink/activities/view_activity.cgi?activity_id=2024