Bio 111: Exam 3 Vertebrates and Invertebrates

Invertebrates

Lack a backbone, more than 95% of known animal species, occupy almost every habitat, very diverse

Phylums of Invertebrates

Porifera, Cnidaria, Lophotrochozoa, Ecdysozoa, Deuterostomia(includes vertebrates)

Porifera (sponges)

-Sedentary
-most live in marine waters
-lack tissues
-lack a body cavity
-filter feeders
-hermaphrodites

Anatomy of a Sponge parts (see notes)

Choanocytes (collar cells), Mesohyl, Pores, and Amoebocytes

Choanocytes (collar cells)

Face inside sponge, Generate a water current through the sponge and ingest suspended food

Mesohyl

A gelatinous noncellular layer between two cell layers in a sponge

Amoebocytes

Found in the mesohyl and play a role in digestion and manufacture of skeletal fibers

Cnidaria

Predators, all possess stinging cells called cnidocytes

-radial
-Gastrovascular cavity (one opening)

Ex. Hydra, Jellyfish, sea anemone, corals

Cnidocytes

Stinging cells in Cnidarians used for both protection and helping them to catch food

Cnidaria body plan

-Diploblastic:
Ectoderm -> Epidermis
Endoderm -> Gastrodermis

-Typically one opening (mouth and anus)

-Some polyp shaped (tentacles top)
-Some medusa shaped (tentacles bottom)

Cnidaria two major clades

Medusozoans and Anthozoans

Medusozoans (Medusa)

-Scyphozoans (jellies)
-Cubozoans (box jellies)
-Hydrozoans (have a medusa form in larva stage)

Anthozoans (only polyps)

-Sea anemones
-Corals

Lophotrochozoa

-Many phylum
-This clade identified by molecular data
-Some develop a lophophore for feeding
-Some pass through a trochophore larval stage

Lophotrochozoa Phylum

-Platyhelminthes
-Syndermata
-Lophophorates
-Molluscs
-Annelids

Platyhelminthes (flatworms)

-Possibly 1st animals with a head
- Most unsegmented (EXCEPT tapeworms)
- Triploblastic, Acoelomate(no body cavity)
- Gastrovascular cavity with one opening (mouth)

-Parasitic Flatworms: Trematodes (flukes) and tapeworms

Syndermata (Rotifers and Acanthocephalans)

-Pseudocoelomates

Rotifers: Many in soil, crown of cilia around mouth

Acanthocephalans: Parasitic worms

Lophophorates (Ectoprocta and Brachiopoda)

- Have a lophophore
-Coelomates (true coelom)

Ectoprocta: Colonial, resemble corals (but have body cavity), sessile

Brachiopoda: Resemble clams (but have a dorsal and ventral shell), marine

Lophophore

Feeding structures bearing ciliated tentacles

Molluscs (Phylum Mollusca)

- Includes snails and slugs, oysters and clams, octopuses and squids

-Most are marine, though some inhabit freshwater, and some snails and slugs are terrestrial

- Molluscs are soft-bodied animals, but most are protected by a calcium carbonate shell

Four Major Classes of Molluscs

- Polyplacophora (chitons): "armor" shell, suction to rocks

- Gastropoda (snails and slugs): most marine

- Bivalva (clams, oysters, mussels, scallops)

- Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses): most marine predators, complex brain

Annelids (Errantia and Sedentaria)

- Coelomates
- Segmented bodies

Errantia: Many body segments, jaws, aquatic worms, most mobile

Sedentaria: Less mobile, Leeches and earthworms

Ecdysozoans

-cuticle
-ecdysis
-Most species-rich animal group

Ecdysozoans Phyla

-Nematodes (roundworms)
-Arthropods
-Tardigrada

Ecdysis

Process where the cuticle is molted

Nematodes (roundworms)

-Free-living or parasitic
-Unsegmented
-Pseudocoelomate
-Cuticle
-Thrashing movement

Tardigrada (water bears)

-Pseudocoelomate
-Survive extreme conditions by cryptobiosis

Arthropods

-Majority of animal species
-Coelomates
-Open circulatory system
-Segmented body, exoskeleton, jointed apppendages, and antennae

-Chelicerates, Myriapods, and Pancrustaceans

Open circulatory system

Blood not in vessels and hemolymph is circulated into the spaces surrounding tissues and organs

Arthropods: Chelicerates

horseshoe crabs and arachnids (spiders, scorpions, mites, and ticks)

Arthropods: Myriapods

centipedes and millipedes

Arthropods: Pancrustaceans

Crustaceans (lobsters, crabs, etc.) and insects

Deuterostomia (includes vertebrates)

-Deuterostome development
-Echinoderms and chordates

Deuterostomia: Echinoderms

- Sea stars, sea urchins, etc.
-Slow-moving or sessile marine animals
- endoskeleton
-Larva bilateral and adult radial
-Coelomates

Deuterostomia: Chordates

Two groups of invertebrates (have notochord in larval stage)

-Lancelet
-Tunicate

Which Phyla are not part of Bilateria?

Porifera and Cnidaria

Metazoa includes all ________________

Animals

Eumetazoa includes all animals except ____________

Porifera

Key characters of chordates (see notes)

1. Notochord
2. Dorsal, hollow nerve cord
3. Pharyngeal gill slits
4. Muscular, post-anal tail

Notochord

A flexible rod between the digestive tube and nerve cord

Dorsal, hollow nerve cord

Develops into central nervous system (CNS) (brain and spinal cord)

Chordates invertebrate clades

Lancelets (Cephalochordata) and Tunicates (Urochordata)

Lancelets (Cephalochordata)

Suspension feeders that retain characteristics of chordate body plan as adults

-Notochord but no vertebrae

Tunicates (Urochordata)

- Metamorphosis from the larva to adult involves resorption of the tail and notochord

-Adults do not retain chordate traits, only in larval stage

Vertebrate derived characteristics

- vertebrae and skull
-neural crest cells

Neural Crest Cells

Form along closing neural tube and give rise to vertebral anatomical structures

Cyclostomes

- Hagfishes (Myxini) and Lampreys (Petromyzontida)
-Lack a backbone, but have rudimentary vertebrae

Hagfishes (Myxini)

- small brain, eyes, ears
-scavengers (eat dead fish)
-Produce slime (predator deterrent)

Lampreys (Petromyzontida)

-notochord and cartilaginous skeleton
- Some parasitic (attach to living fish)

Gnathostomes

- Have jaws
- enhanced forebrain, smell, and vision
-Lateral line system
- Mineralized skeleton (with calcium phosphate)

Lateral line system

Rows of organs sensitive to vibrations that are located along each side of the body of aquatic gnathostomes

Chondrichthyans

- Sharks, Rays, and relatives (ratfish)
-Cartilaginous skeleton
-Aquatic gnathostomes

Osteichthyes

- Bony endoskeleton (with calcium phosphate matrix)
- Hinged jaws
-Paired fins, independently moveable
-External keratinous structures (scales, nails, etc.)

Ray-finned fish (Actinopterygii)

- Perch, lion fish, sea horse, etc.
-bony skeleton
-Maneuverable fins supported by rays

Anatomy:
> Swim-bladder= buoyancy
>gills= respiration
> lateral line= detect vibration, pressure

Lobe-Finned Fish

-Muscular fins or limbs
-Rod shaped bones

-Fins of some lobe-fins evolved into limbs and feet of tetrapods

-Coelacanths (Actinistia) and lungfishes (Dipnoi)

Coelacanths (Actinistia)

Ancient lineage of aquatic lobe-fins still surviving in Indian Ocean

Lungfishes (Dipnoi)

-Freshwater lobe-fins with both lungs and gills
-Sister group of tetrapods

Tetrapod derived characteristics

-Four limbs and feet with digits
-A neck, enabling independent movement of the head
-Fusion of the pelvic girdle to the backbone
-The absence of gills (except some aquatic species)
-Ears for detecting airborne sounds

Tiktaalik "fishapod"

Shows both fish and tetrapod characteristics

Amphibia

-4 limbs
-Most have moist skin for gas exchange
- Most semi-aquatic stage

-Salamanders, frogs, and Caecilians

Amphibia: Salamanders

- "tailed ones"
-simple lungs
- Aquatic larval stage
-Axolotl (exhibit paedomorphosis)

Paedomorphosis

the retention of juvenile features in sexually mature organisms, common in aquatic salamanders

Amphibia: Frogs

- "Tailless ones"
- Toads= thicker skin
- Aquatic larval stage

Amphibia: Caecilians

- Burrow in ground
-Live young or hatch from eggs

Amniotes

- Terrestrial tetrapods with amniotic egg
- Rib cage ventilation

- Reptilia and Mammalia

Amniotes derived characters

- Amniotic eggs
- Multilayer, water-proof skin
- Both juveniles and adults have lungs
- Use rib cage to ventilate lungs
- Lungs have lots of surface area

Amniotic eggs

- Contains membranes that protect the embryo
- Most have a shell
- Key adaptation for life on land (shell protects from drying out)

Extraembryonic membranes (see notes)

-Allantois= waste storage and removal

-Chorion= Gas exchange between embryo and external environment

-Amnion= fluid sac for shock absorption and buoyancy

-Yolk sac= provides nutrients for developing embryo

Reptilia

- scales for waterproof barrier (or feathers in birds)
- Most lay eggs on land and internal fertilization
-Most ectothermic, except birds endothermic

- Lepidosaurs, Testudines, Crocodila, and Aves

Reptilia: Lepidosaurs (tuatara, snakes, and lizards)

Tuatara: was highly diverse during Mesozoic, now only one extant species

Snakes and Lizards: Upper jaw is moveable, which accommodates larger prey

Reptilia: Testudines (turtles)

Shell with fused vertebrae, clavicles, and ribs

Reptilia: Crocodilia (crocodiles, alligators, and caymans)

4-chambered heart, thoracic breathing

Reptilia: Aves (birds)

-Wings with keratin feathers

- Weight-saving adaptations improve efficiency of flight (no urinary bladder, 1 ovary, small gonads, and loss of teeth)

Mammalia

-Have hair and produce milk

-Monotremes, Marsupials, and Eutherians

Mammals derived characters

- Mammary glands
- Hair and fat layer under skin for insulation
- Kidneys, conserve water from watse
- Endothermy and high metabolic rate
- Efficient respiratory and circulatory systems
- Large brain to body size ratio
- Extensive parental care
-Differentiated teeth

Ectothermic

Absorbing external heat as the main source of body heat

Endothermic

Capable of maintaining body temperature through metabolism

Mammalia: Monotremes

Small group of egg-laying mammals consisting of echidnas and platypus

Mammalia: Marsupials

- Opposums, Kangaroos, and Koalas

- Embryo develops within the mother's uterus and is nourished by the placenta
-Born very early in development and completes embryonic development while nursing in maternal pouch called a marsupium

Mammalia: Eutherians (placental mammals)

- More complex placenta than marsupials
- Complete embryonic development within a uterus, joined to the mother by the placenta

Deuterostomia Clades

-Echinodermata (NOT CHORDATES)
- Cephalochordata (lancelets)
- Urochordata (tunicates)
- Myxini (hagfishes)
- Petromyzontida (lampreys)
- Chondrichthyes (sharks, rays, and relatives)
- Actinopterygii (ray-finned fishes)
- Actinistia (coelacanths)
- Dipnoi (lungfishes)
- Amphibia
- Reptilia
-Mammalia

______________ are the sister group to chordates

Echinodermata

What clades make up Cyclostomes?

Myxini (hagfishes) and Petromyzontida (lampreys)

What clades make up tetrapods?

Amphibia, Reptilia, and Mammalia