Chapter 34 Animal Diversity

What is a Porifera (sponges)?

• Organisms with tiny holes (pores) all over their body

• Simplest animals, no true tissues/organs, specialized cells (choanocytes)

What is a choanocyte?

Sponges (Porifera)

• a flagellated collar cell that creates water flow and traps food

How do sponges feed?

• Filter feeding: water enters pores → choanocytes trap food → amoebocytes distribute nutrients

Do sponges have tissues or organs?

• No, only specialized cells

What are key traits of Cnidarians and examples?

• Radial symmetry

• mouth surrounded by tentacles

• A closed gastric cavity

• 2 tissue layers (endodermis & epidermis)

ex. jellyfish, hydra, coral

What is the difference between sponges (porifera) & cnidarians?

• Sponges lack tissues and are filter feeders

• Cnidarians have true tissues, digestion and are predators

What are cnidocytes and nematocysts?

Stinging cells with harpoon-like structures used to capture prey

• Cnidocyte - the whole cell (weapon)

• Nematocyst - the harpoon-like organelle coming out weapon to capture prey

What is the gastrovascular cavity?

• A cavity with one opening that acts as both mouth & anus

How do cnidarians digest food?

• First extracellularly in the gastrovascular cavity, then intracellularly inside cells.

What are the key traits of bilaterians?

• Bilateral symmetry

• 3 tissue layers (ectoderm, mesoderm, endoderm)

• Cephalization

• Complex organs

(Bilateria) What is cephalization?

• Head development with concentrated nervous tissue and sensory organs at the front

(Bilaterians, Protostomes) What are Lophotrochozoa?

• Major group of bilaterians making up half of animal phyla

• Has “lophophore” (a tentacle-lined organ for filter feeding) and/or “trochophore” (a type of larva)

(Bilaterians, Protostomes, Lophotrochozoa) What are the traits of annelids?

• Segmented body, true coelom, closed circulatory system

(Bilaterians, Protostomes, Lophotrochozoa) What are the traits of mollusks?

• Soft body, mantle, foot, sometimes a shell

(Bilaterians, Protostomes) What are Ecdysozoans?

•Animals that occasionally molt (shed) their external layer (exoskeleton)

•Nematodes and arthropods → most abundant and diverse phyla

(Bilaterians, Protostomes, Ecdysozoa) What are traits of arthropods?

• Chitin exoskeleton, segmented body, jointed appendages

(Bilaterians, Protostomes, Ecdysozoa) Why are arthropods so diverse?

• Segment specialized and adaptability

(Bilaterians, Protostomes, Ecdysozoa) Why are insects the most diverse animals?

• Wings, small size, rapid reproduction, metamorphosis, makes up 80% of animals

(Bilaterians, Protostomes, Ecdysozoa) What is the advantage of metamorphosis?

• Reduces competition between life stages

(Bilaterians, Deuterostomes) What are Chordates?

• Animals that share a specific set of features at some point in their life cycle (even if only as embryos).

• Includes vertebrates animals

(Bilaterians, Deuterostomes) What are the 4 key chordate traits?

• Notochord

• Dorsal hollow nerve chord

• Pharyngeal slits

• Post-anal tails

(Bilaterians, Deuterostomes, Chordates) What are vertebrates?

• Chordates with an internal skeleton and cranium

• Ex. fish, amphibians, reptiles, birds, mammals

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are the traits of jawless fish?

• No jaws

• Cartilage cranium

• Ex. hagfish & lamprey

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are the traits of cartilaginous fish?

• Jaws

• Cartilage skeleton, no true bone

• Teeth made of calcium phosphate (bone)

• Ex. sharks & rays

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are the traits of bony fish?

• Jaws

• Bone skeleton

• Bones made of calcium phosphate

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are the traits of lobe-finned fish?

• Fleshy fins with bone

• Ancestors of tetrapods

• Ex. coelacanth & lungfish

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are tetrapods?

• Vertebrates with 4 limbs that moved from water to land

(Bilaterians, Deuterostomes, Chordates, Vertebrates) What are key tetrapod features?

• Bony cranium

• Eyes & mouth

• Internal skeleton

• 4 limbs

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods) What are amphibian traits?

• Live in water and land

• Moist skin & no hair

• Lay eggs in water

• ex. frogs, salamanders, and caecilians

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods) What is an amniote?

• A vertebrate whose embryo develops inside an amniotic egg (an egg with protective membranes).

• ex. reptiles, birds, and mammals

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods) What are features of the amniotic egg?

• Yolk or placenta for nutrition

• Amnion for protection

• Shell prevents drying

• Allows life on land

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods, Amniotes) What are traits of mammals?

• Produce milk

• Hair

• Warm-blooded

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods, Amniotes) What are the 3 groups of mammals?

• Monotremes

• Marsupials

• Placental Mammals

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods, Amniotes, Mammals) What are monotremes?

• Egg-laying mammals

• Ex. platypus, echidnas (spiny anteaters)

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods, Amniotes, Mammals) What are marsupials?

• Short pregnancy

• Development in pouch

• Ex. kangaroos, koalas

(Bilaterians, Deuterostomes, Chordates, Vertebrates, Tetrapods, Amniotes, Mammals) What are placental mammals?

• Long development in uterus

• Ex. humans, primates (gorillas, chimpanzees), dogs

What are major trends in animal evolution?

• Increasing complexity; symmetry (none → radial → bilateral)

• Cephalization (Head development with concentrated nervous tissue and sensory organs at the front)

What is a deuterostome?

• Anus forms first, then mouth

What is a protostome?

• Mouth forms first, then anus