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