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BIO 102 Flashcards

Phylum Arthropoda

  • Arthropod Definition: From Greek words "Arthron" (joint) and "Pous" (foot), denoting organisms with jointed legs/appendages.
  • Phylum Arthropoda: Largest phylum in the animal kingdom, including centipedes, insects, millipedes, mites, spiders, crabs, lobsters, etc.
  • Prevalence: About 84% of all known animals belong to this phylum.
  • Habitat: Found in every habitat on Earth with great variety of adaptations (aquatic, terrestrial, flight).
  • Diversity: Over 10 million species known.

General Characteristics of Phylum Arthropoda

  1. Body Divisions: Head, thorax, and abdomen.
  2. Segmentation: Body is metamerically segmented.
  3. Appendages: Three pairs of jointed appendages (some have more).
  4. Compound Eyes: Present with several thousand lenses for larger vision.
  5. Antennae: Present.
  6. Symmetry & Layers: Bilaterally symmetrical, triploblastic, and segmented.
  7. Organization: Organ and system grade.
  8. Exoskeleton: Made of chitin; no bones present.
  9. Respiratory System: Via general body surface, gills, tracheae, or lung book.
  10. Circulatory System: Open circulatory system with dorsal heart.
  11. Excretion: Malpighian tubules or green gland.
  12. Nervous System: Dorsal brain with ventral nerve cord.
  13. Sexes: Separate; sexual dimorphism present.
  14. Fertilization: Internal (few external).
  15. Development: Direct or indirect with larval stages.

Classification of Phylum Arthropoda

  • Phylum Arthropoda
    • Sub-Phylum: Trilobitomorpha, Chelicerata, Crustacea, Myriapoda, Hexapoda
    • Classes: Various classes within each sub-phylum (e.g., Merostomata, Arachnida, Chilopoda, Insecta, etc.)

Sub-Phyla of Arthropoda

Sub-Phylum Trilobitomorpha

  • Group: Trilobites.
  • Time Period: Dominant arthropods in the early Paleozoic seas (540-250 million years ago).
  • Extinction: Became extinct 298-251 million years ago at the end of the Paleozoic era.
  • Characteristics:
    1. Extinct.
    2. Head (cephalon) with 5 segments, a pair of antennae, and compound eyes.
    3. Flattened body: cephalon, thorax, and pygidium.
    4. Each segment has 3 lobes; each segment bears a pair of similar branched appendages.
  • Fossil Species: More than 4,000 fossil species are known.

Sub-Phylum Chelicerata

  • Habitat: Mostly on land.
  • Body Divisions: Prosoma (cephalothorax) and opisthosoma (abdomen).
  • Antennae: Absent.
  • Abdomen: Divided into 13 segments.
  • Appendages:
    • First pair: Chelicerae flanking the mouth.
    • Four pairs of interior appendages.
  • Respiration: Trachea or gills.
  • Excretion: Malpighian tubules.
Classes of Chelicerata
  • Arachnida: Scorpions, spiders, ticks, mites, etc.
  • Merostomata: Water/Sea Scorpion, Horseshoe crab.
  • Pycnogonida: Sea spider.

Sub-Phylum Crustacea

  • Habitat: Mainly aquatic (crab, shrimps, copepods etc).
  • Appendages:
    • Two pairs of antennae.
    • A pair of mandibles.
    • Two pairs of maxillae.
  • Head & Thorax: Head fused with thorax (Cephalothorax).
  • Carapace: Body covered with a single large carapace.
  • Legs: 5 pairs of appendages.
  • Excretion: Green glands or antennal glands.
  • Eyes & Gonopores: A pair of compound eyes and gonopores present.
  • Development: Indirect; larval stage present.
Classes of Crustacea
  • Branchiopoda: Fairy Shrimp, Clam Shrimp, tadpole Shrimp, Water Fleas etc.
  • Remipedia: Cave-dwelling Blind Shrimps.
  • Cephalocarida: Horseshoe Shrimps.
  • Maxillopoda: Barnacles etc.
  • Ostracoda: Seed Shrimp etc.
  • Malacostraca: Phyllocarids, mole Crabs, lobsters.

Sub-Phylum Myriapoda

  • Habitat: Chiefly terrestrial.
  • Body: Elongated with numerous segments.
  • Head: Antennae, 2 pairs of jaws, and a pair of simple eyes.
  • Legs: Numerous.
  • Lips: Epistome and labrum (upper), maxillae (lower).
  • Respiration: Trachea.
  • Excretion: Malpighian tubules.
Classes of Myriapoda
  • Chilopoda: Centipedes
  • Diplopoda: Millipedes
  • Pauropoda: Pauropus amicus
  • Symphyla: Scollopendrellid, Scutigerella

Sub-Phylum Hexapoda

  • Habitat: Mostly terrestrial.
  • Body Divisions: Head, thorax, and abdomen.
  • Head: Bears a pre-segmental acron.
  • Thorax: Three segments (prothorax, mesothorax, and metathorax).
  • Abdomen: 7-11 segments.
  • Appendages: Three pairs of jointed appendages.
  • Eyes: A pair of compound eyes.
  • Respiration: Through trachea.
  • Excretion: Malpighian tubules.
  • Development: Indirect; larval stages present.
Classes of Hexapoda
  • Entognatha: Wingless and ametabolous arthropods. Mouthparts are entognathous (retracted within the head). Apterous (lack wings).
  • Insecta:
    • Body divided into head, thorax, and abdomen.
    • Abdomen usually 11 segments without appendages.
    • Head bears simple eyes and a pair of lateral (side) compound eyes.
    • Thorax segmented into three with each bearing a pair of legs.
    • Second and third thorax usually bears wings.
Orders of Insecta
  • Coleoptera: Beetles.
  • Orthoptera: Locusts, Grasshoppers, and Crickets.
  • Lepidoptera: Moths, Butterflies.
  • Hymenoptera: Bees, Wasps, and Ants.
  • Diptera: Flies, Mosquitoes.
  • Odonata: Dragonflies, Damselflies.
  • Isoptera: Termites.
  • Hemiptera: True bugs.
  • Siphonaptera: Fleas.

Phylum Platyhelminthes (Flatworms)

  • Kingdom: Animalia.
  • Characteristics: Triploblastic, bilaterally symmetrical, dorsoventrally flattened, acoelomate flatworms with an organ grade of construction without a definite anus, circulatory, skeletal or respiratory system but with protonephridial excretory system and mesenchyme filling the space between the various organs of the body.

General Characteristics

  1. Symmetry/Layers: Triploblastic, Acoelomate, Bilaterally symmetrical.
  2. Lifestyle: Free-living, commensal, or parasitic.
  3. Body Covering: Soft covering with or without cilia.
  4. Body Shape: Dorsoventrally flattened without segments (leaf-like).
  5. Systems: Devoid of anus and circulatory systems but have a mouth.
  6. Respiration: Simple diffusion through body surface.
  7. Digestive System: No digestive system/tract (in some it is branched and incomplete).
  8. Parenchyma: Connective tissue that helps in transportation of food materials.
  9. Reproduction (Sex): Mostly hermaphrodites (Monoecious).
  10. Reproduction (Modes): Sexually by fusion of gametes and asexually by regeneration and by fission.
  11. Fertilization: Internal.
  12. Life cycle: Complicated with one or more larval stages.
  13. Excretion: Flame cells help in excretion and osmoregulation.
  14. Nervous System: Brain and two longitudinal nerve cords arranged in a ladder-like fashion.
  15. Skeleton: Exo and endoskeleton completely absent.

Classification of Platyhelminthes

  • Classes: Turbellaria, Trematoda, Cestoda

Class Turbellaria (Planarians)

  • Origin of Name: Latin Turbell = a little string
General Characteristics
  1. Lifestyle: Mostly free living but some are commensal or parasitic.
  2. Habitat: Terrestrial, marine or freshwater but mostly bottom dwellers.
  3. Body: Flat, ribbon-like or leaf-like with unsegmented body covered with ciliated cellular or syncytial epidermis.
  4. Mouth: Ventral. Intestine precedes by a muscular pharynx.
  5. Adhesion: Adhesive organs abundantly present.
  6. Excretion: Protonephridia; flame cell.
  7. Life Cycle: Simple.
  8. Reproduction: Mostly reproduce sexually, asexually or by regeneration.
Feeding and Digestion
  • Incomplete digestive tract with mouth, no anus.
Nervous System and Senses
  • Distinct head with cephalic ganglia.
  • Pair of ventral nerve cord connected by ladder-like interconnections.
  • Sense organs concentrated on the head.
    • 2 eyespots – oceli
    • Auricles - contain tactile cells/chemoreceptors.
    • Some have statocysts for reaction to gravity.
  • Examples: Planaria, Otoplana, Dugegia etc and about 4,500 species are known.

Class Trematoda (Flukes)

  • Species: Over 3 times more species than any other classes of flatworms.
General Characteristics
  1. Lifestyle: Ecto or endoparasites.
  2. Body: Unsegmented and dorsoventrally flattened.
  3. Tegument: Thick but without cilia or rhabdites.
  4. Body Covering: Body undivided and covered with cuticle.
  5. Attachment: Suckers and sometimes hooks are present.
  6. Digestive Tract: Incomplete; consist of the anterior mouth, simple pharynx and two forked or many branched intestine; anus absent.
  7. Nervous System: 3 pairs of longitudinal nerve cord.
  8. Excretion: Protonephridial excretory system consisting of flame cells.
  9. Reproduction: Monoecious.
  10. Organs: Single ovary, 2 or more testes.
  11. Development: Direct (in ectoparasites) or indirect (in endoparasites) with alternation of hosts.
  12. Body Wall: Covered by thin flexible cuticle and integument is syncttium (not divided into individual cells) with no cilia.
Feeding and Digestion
  • Well developed incomplete digestive tract. Mouth is anterior.
Reproduction
  • Mostly are monoecious capable of self-fertilization.
  • Life cycle: Complex with one or more larval forms occurring in intermediate host and adults in definite hosts. Adults are typically parasites of fish or other vertebrates.
Typical Life Cycle
  • Egg: Usually out of faeces, must reach water to develop
  • Miricidium: Free swimming larva, penetrate tissue of snail
  • Sporocyst: Reproduces asexually to yield more sporocyst or radiae
  • Radia: Also reproduces asexually to produce more radiae or cercariae
  • Cercaria: Emerge from snail, penetrate second host or encyst in vegetation to become Metacercaria juveline
  • Metacercaria: Juvenile fluke, when eaten by definitive host develop into adult fluke.
  • Examples:
    1. Clonorchis sinensis (Chinese Liver Fluke)
    2. Fasciola hepatica (Sheep Liver Fluke)
    3. Schistosoma (Blood Fluke and its dioecious)
      • Schistosoma mansoni
      • Schistosoma japonicum
      • Schistosoma haematobium
      • Schistosoma intercalatum
      • Schistosoma mekongi
      • Schistosoma bovis etc
    4. Paragonimus westermani (Lung fluke)

Class Cestoda (Tapeworms)

  • Origin of Name: Greek: Ketos (gridle) + eidos (form)
General characteristics
  1. Lifestyle: Exclusively parasitic.
  2. Habitat: Endoparasites in the intestine of vertebrates.
  3. Body: Divided into many segments (proglottids but rarely undivided, elongated flat ribbon-like.
  4. Integument: Without microvilli.
  5. Body Covering: Without epidermis and cilia but covered with cuticle.
  6. Scolex: Anterior end is provided with adhesive structures (hooks and suckers) except in cestodaria.
  7. Digestive System: Mouth and digestive system totally absent.
  8. Excretion: Consist of protonephridia.
  9. Nervous System: Comprises of a pair of ganglia and 2 lateral longitudinal nerve cords.
  10. Proglottids: Each mature segment or proglottids is momoecious
  11. Life Cycle: Complicated with 2 or more hosts.
  12. Embryos: Possess hooks.
  13. Body Plan: Different from other flatworms. No head, the front end is called scolex with hooks and suckers used for attachment and not for feeding.
  14. Tegument: Syncytial (not sub divided into separate cells) with microvilli to increase surface area for absorption.
  15. Cuticle: Tegument secrete protective cuticle.
  16. Feeding and Digestion: Lack digestive system.
  17. Nervous System: Simple nervous system. Proglottids connected by nerve cords.
  18. Excretion: Similar to that of flatworms
  19. Proglottids (Function): Each proglottids act as individual. Any 2 proglottids can exchange sperm.
  20. Proglottids (Eggs): When gravid, each proglottids can carry up to 100,000 eggs each.
Life Cycle
  • Almost all tapeworm require at least 2 host; mainly vertebrates.
  • All are monoecious.
  • Mature proglotteids are farther away from the scolex.
  • Eggs or mature proglottids are shed in faeces.
  • Once egg is released. It must be ingested by an intermediate host (another vertebrate)
  • Once egg is ingested, larva hatch and bore through intestine of host and into blood.
  • Travels to skeletal muscle, heart and other organs. Secrete a protective cyst.
  • In some, cyst develop into bladder worm or cysticercus.
  • Humans can get infected with eggs by unsanitary habits with faeces, not washing of hands, kissing pets etc or eaten poorly cooked beef or pork.
  • Examples:
    1. Taenia saginata (beef tapework)
    2. Taenia solium (Pork tapeworm
    3. Diphylobothrium latum (fish tapeworm)
    4. Diphylidium caninum (flea tapeworm)
    5. Ecjinococcus granulosus (Hydatid worm/ dog tapeworm)

Phylum Echinodermata

  • Origin of Name: Echinodermata word has been derived from: Echinos = Hedge hog/ Uneven/ Rough or Spiny . Derma = Skin
    *Animals having uneven or spiny skin are called Echinodermata
  • Definition: An echinoderm is a marine invertebrate of the phylum Echinodermata.
  • Examples: sea stars, sea lilies, feather stars, brittle stars, sea cucumbers, and sea urchins.
  • Habitat: All marine; found in all oceans at all depths and almost all are bottom dwellers. A few are pelagic swimmers and a few are commensal.
  • Color: Mostly drab (dull) colours but a few are red, orange, purple, blue, etc

General Characteristics

  1. Appearance: Star-like, spherical, or elongated.
  2. Habitat: Exclusively marine animals.
  3. Skin: Spiny-skinned.
  4. Organization: Organ-system grade of body organization.
  5. Symmetry: Triploblastic, coelomate and radial symmetrical animals often pentamerous also.
  6. Body: Unsegmented with globular, star-like, spherical, discoidal or elongated shape.
  7. Head: Absent; body surface is marked by five symmetrically radiating areas (ambulacra) and five alternating interradii (inter-ambulacra).
  8. Endoskeleton: Endoskeleton of dermalcalcareous ossicles with spines, covered by the epidermis.
  9. Water-vascular system: A peculiar water-vascular system of coelomic origin, including podia or tube feet for locomotion and usually with a madreporite.
  10. Coelom: Coelom of enterocoelous type constitute the perivisceral cavity and cavity of the water vascular system.
  11. Alimentary Canal: Straight or coiled.
  12. Vascular System: Vascular system and haemal system, enclosed in coelomic perihaemal channels.
  13. Respiratory organs: Include dermal branchiae, tube feet, respiratory tree and bursae.
  14. Nervous System: Without a brain and with a circumoral ring and radial nerves.
  15. Sense Organs: Poorly developed sense organs include tactile organs, chemoreceptors, terminal tentacles, photoreceptors and statocysts.
  16. Excretory organs: No excretory organs.
  17. Reproduction: Usually dioecious, and fertilization is external.
  18. Development: Indirect through free-swimming larval forms.

Classification

  • Phylum: ECHINODERMATA
    • Sub-Phylum: ELEUTHEROZOA PELMATOZOA
    • CLASS: ASTEROIDEA CRINOIDEA HOLOTHUROIDEA ECHINOIDEA OPHIUROIDEA

Class Asteroidea

General Characteristics
  • Living species
  • Flattened, star-shaped body with five arms.
  • Tube feet with suckers.
  • Respire through papulae.
  • Body comprises of calcareous plates and movable spines.
  • Pedicellaria (a defensive organ like a minute pincer) is present.
  • Free moving, inhabit all seas except low salinity areas
  • Bottom dwellers and mostly found on hard rocky surfaces
  • Many live in deep ocean, also common along littoral zone in coastal waters where they may congregate in very large numbers
  • Usually 1cm to 1m in diameter
  • Best representatives of the basic features of the phylum
  • Body composed of rays (arms) projecting from a central disc
  • Arms not sharply set off from central disc, in some arms are very short eg. Culcita, a pentagon with no arms, mouth and 100’s of tube feet underneath
  • Typically pentamerous symmetry, most with 5 arms (sunstar up to 40 arms, some have up to 50 arm) Eg., Asterias, Zoroaster, Starfish, sea stars, sea daisie

Class Holothuroidea

General Characteristics
  • 1150 living species
  • make up 90% of biomass on deep ocean floor. Often on sandy or muddy bottoms, some crawl on sea floor while others hide beneath rocks. Some are burrowers
  • range from 3 cm to 1m long
  • most are black, brown, or olive green
  • The body is long and cylindrical.
  • The arms, spines, and pedicellariae are absent.
  • They respire through the cloacal respiratory tree.
  • They possess tube feet with suckers.
  • like sea urchins have no arms, have ambulacral areas instead
  • tend toward bilateral symmetry: polar axis is elongarted so some become
  • long and wormlike or “cucumber shaped” “U-shaped”
  • with mouth and anus are on opposite ends
  • bottom side (sole) on which they crawl
  • body has a leathery appearance
  • in most the ossicles are greatly reduced to microscopic plates embedded in body wall
  • a few are covered in armor of calcareous plates
  • mouth is always surrounded by 10-30 tentacles (modified tube feet) which are part of the water vascular system
  • tentacles are highly retractile, can be completely retracted into mouth
  • tube feet can also be modified into sensory papillae, fins, sails, etc Eg., Cucumaria, Holothuria, Sea cucumber

Class Echinoidea

General Characteristics
  • 950 living species
  • The body is hemispherical.
  • The tube feet contains suckers.
  • The body does not have arms.
  • The body has a compact body enclosed within a test (or shell) of closely fitting ossicles or plates and movable spines.
  • widely distributed in all seas
  • all are benthic, remain close to the substrate
  • no arms, but 5 ambulacral areas on test through which very long tube feet extend
  • many have developed a secondary bilateral symmetry
  • with numerous long moveable spines
  • most 6-12 cm dia; a few to 36 cm
  • Eg., Echinus (Sea Urchin), Cidaris, sand dollar, heart urchins, sea biscuitsBody Form

Class Ophiuroidea

General Characteristics
  • >2,000 living species
  • not as diverse in structure as asteroids but probably the most advanced class of echinoderms also, the
  • most active of the phylum, found in all types of marine benthic habitats and mainly benthic.
  • The body is flat with pentamerous discs.
  • The tube feet are devoid of suckers.
  • They respire through Bursae.
  • The long arms are demarcated from the central disc.
  • tend to be secretive in cracks and crevices on hard substrates.
  • some can burrow, a few can swim and up to 12 cm diameter
  • most are fairly drab, a few are highly colored
  • leathery skin and few cilia. have arms with central disc but:
  • long thin arms sharply set off from disc.
  • no ambulacral groove, tube feet (podia) play little role in locomotion
  • visceral organs are confined to central disc
  • typically 5 arms, but in basket stars they repeatedly branch to produce tentacle like mass Eg. Ophiderma, Amphuria, brittle stars, basket stars, serpent stars

Class Crinoidea

General Characteristics
  • 625 living species
  • The body is star-shaped.
  • The tube feet have no suckers.
  • The arms are bifurcated.
  • Spines and pedicellariae are absent.
  • an ancient group; many fossil species
  • some are stalked sessile animals
  • others are free living and motile
  • can swim or crawl short distances; many are deep water forms
  • most live at depths of 100m or more but a few are found in the intertidal zone
  • Body Form: flower shaped body
  • sometimes attached to the end of a stalk
  • body disc (calyx) is covered in leathery skin covering calcareous ossicles
  • upper surface of calyx bears mouth and anus
  • arms have pinules giving feather-like appearance, stalk if present, sometimes has cirri
  • no madreporite, spines or pedicellariae
  • the water vascular system uses coelomic fluid
  • no madreporite to take in seawater directly Eg., Neometra, Antedon, Sea lily, feather stars