BIOL 125 - Intro to Animals, Protostomes, Deutrostomes

What are the types of symmetry?

1. Radial

2. Bilateral

3. Biradial

Radial Symmetry

Many planes of symmetry around a central point

- Believed to be the first symmetry

Biradial Symmetry

Two planes of symmetry

Bilateral Symmetry

Distinct left and right part to body

Only one plane of symmetry

Benefits of radial symmetry

Useful for sessile organisms so they can detect a threat from all directions and be able to feed in all directions

Benefits of bilateral symmetry

Formation of head and tail region

Good for motile organisms

Three types of body cavities

1. Acoelomate

2. Pseudocoelomate

3. Eucoelomate

Acoelomate

Animal that lacks a coelom or body cavity

- Gut surrounded by tissue of embryonic mesoderm

- Evolved multiple times

Pseudocoelomate

- Fluid fileld chamber, inside the gut is made up of endoderm

- The pseudocoelom is located between the gut and the outer body wall.

Cnidaria: What are the four groups?

1. Hydrozoa

2. Anthozoa

3. Cubozoa

4. Scyphozoa

Hydrozoa

Group in Cnidaria

- Hydra and Portugese Man O' War

Anthozoa

Group in Cnidaria

- Sea anemones and sea coral

Cubozoa

Group in Cnidaria

- Box jellies

Scyphozoa

Group in Cnidaria

- True jellies

Life cycle of Cnidaria

- Similar to plant (alternation of generations) but between two adult forms (polyp and medusa)

1. Polyp: Sessile form where mouth points away from substrate, does asexual reproduction to form medusa

2. Medusa: Moving form, does sexual reproduction to produce polyps

- oral: where mouth is aboral: opposite of mouth

- Dioecious: two sexes, one producing eggs and one produce sperm

Cnidaria - Characteristics

- Has a stinging cell, usually on feeding structure

- Has a bulb of venom, and modified cilia act as trigger

- Radial symmetry

- Diploblastic: two germ layers in embryo, no mesoderm, has an ectoderm

Cnetophora - what are they ?

Comb Jellies

Cnetophora- Anatomy

- Biradial symmetry (paired tentacles, double internal canals)

- Two cell layers thick (epidermis and one that lines gastric track called the gastridermis)

- Comb Plates : Used for swimming

- Colloblasts : glue cells, discharge to grab hold of stuff

- Sexual reproduction and monoecious

Lophotrochozoa: What are the four groups?

1. Rotifers

2. Platyhelminthes

3. Molluscs

4. Annelids

Lophotrochozoa- Characteristics

- Based on molecular characteristics; not all in the group have these

1. Locophore : Retractable feeding structure, ciliated, mouth at base, ciliate(s) that generate flow of water

2. Trochophore : Larva have bands of cilia, U-shaped digestive band of cilia generate flow of water, anus has cilia too

3. Spiral cleavage : all have these except rotifers

Rotifers

Group in Lophotrochozoa

- Marine or freshwater filter feeders

- Mastax : Where food is chewed

- Wheel organ where food goes in

- Pseudocoelomate

- Protonephridia

- Parthenogenesis

Parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs.

- All female no males

- Rotifers do this!

Platyhelminthes - What are the four groups?

1. Turbellaria

2. Trematoda

3. Monogenea

4. Cestoda

Turbellaria

Group in Lophotrochozoa, Platyhelminthes

- Free living flat worms

- Ex. planaria, marine worms

Trematoda

Group in Lophotrochozoa, Phylum Platyhelminthes

- Parasitic : Flukes

Monogenea

Group in Lophotrochozoa, Phylum Platyhelminthes

- Parasitic :Monogenetic flukes

Cestoda

Group in Lophotrochozoa, Phylum Platyhelminthes

- Parasitic : Tape worms

Tape worm life cycle and anatomy

egg (from feces) -> oncosphere (intermediate host) -> metacestode (larval in intermediate. extra intestinal) -> adult (host)

- Proglottids : Reproduction structure

- Scolex : Attachment structure

- Tape worms hang out in the duodenum, absorbs nutrients from the host

- Scolex is not the head, has no mouth or brain

Platyhelminthes - What are they and characteristics

Group in Lophotrochozoa

- Flat worms

- Acoelomate

- Protonephridia

Molluscs - Characteristics and Anatomy

Group in Lophotrochozoa

- Triploblastic

- Eucoelomate

- Bilateral symmetry

- Radula : Feeding structure, tongue with teeth, pushes along surface and scrapes off food

- Mantle cavity : Thick layer of tissue that surrounds visceral mass, underneath the shell

- Trochophore larva : Turns into Veliger (more motile)

Molluscs - What are the three groups ?

1. Gastropoda

2. Bivalvia

3. Cephalopoda

Gastropoda

Group in Lophotrochozoa, Phylum Molluscs

- Univalve, missing or reduced valve

- Slugs and snails

Bivalvia

Group in Lophotrochozoa, Phylum Molluscs

- No head or radula

- Clams, scallops, oysters,

Cephalopoda

- Have a head foot

- Reduced shell in most

- Cuttlefish, octopus, squid

Annelids - Characteristics and Anatomy

Group in Lophotrochozoa

- Segmented worms (look like they have rings)

- Prostomium - First segment of body, where mouth is

- Peristomium - Second segment of body, around the mouth

- Trunk - Main portion of body

- Pygidium - Last segment of body, where anus is

Annelids - What are the three groups?

1. Polychaeta

2. Clade Clitella (monophyletic)

a) Oligochaeta

b) Hirudinea

Polychaeta

Group in Lophotrochozoa, Phylum Annelids

- Poly (many) chaeta (bristles)

- Polyphyletic group

- Paired parapodia : Finger like projections on each segment, used for movement, anchoring, swimming, and sometimes gills

- Burrowing and filter feeder forms

Oligochaeta

Group in Lophotrochozoa, Phylum Annelids, Clade Clitellata

- Earth worms

- Paraphyletic group

- Have few bristles (Olig = few)

- No parapodia or gills

Hirudinea

Group in Lophotrochozoa, Phylum Annelids, Clade Clitellata

- Leeches

- No bristles

- No parapodia or gills

Ecdysozoa characteristics

- Grow incrementally, add length, require molting

- Non elastic cuticle or exoskeleton (hardened cuticle)

- Ecdysis : Word for molting

Nemata - Characteristics and anatomy

Group in Ecdysozoa

- Collagenous cuticle; somewhat elastic, needs to shed cuticle

- Longitudinal muscles only

- Pseudocoelomate

- Many are parasitic

Nemata - What are the three groups?

1. Ascaris

2. Trichinella

3. Enterobius

Ascaris

Group in Ecdysozoa , Phylum Nemata

- Intestinal roundworm

- Most common in humans

Trichinella

Group in Ecdysozoa , Phylum Nemata

- Muscle parasites

Enterobius

Group in Ecdysozoa , Phylum Nemata

- Pinworm

Syncytial Ciliate Hypothesis

Theory about how multicellular organisms evolved from a single-celled organism

- Not supported by molecular evidence

- Built upon idea that larval form of cnidarians; assumed ancestors looked alike

- Sponges and choanoflagellates look very similar

- Syncytial : structure that is made up of multiple nuclei enclosed by one cell

Colonial Flagellate Hypothesis

Sponges have a type of cell called a choanocyte; Proposed ancestor of all animals was a colonial choanoflagellate

- Molecular evidence supports this

- Most likely scenario

Animal themes

How people thought to break up animals into groups before molecular grouping was confirmed better

1. Origin of tissues

2. Body cavity

3. Symmetry

4. Metamerism

5. Embryonic development : often used still

Eucoelomate

An organism that has a complete body cavity where the ectoderm and the endoderm is lined by mesoderm

- Body cavity is not fluid-filled

- Mesoderm : Muscular tissue

- Ectoderm : Outer layer

- Mesoderm surrounds coelom

- Ex: humans, annelids, anthropods

Metamerism

Segmentation

- Division of body with repeated segments and organs

Advantages of metamerism

Efficient locomotion : Multiple segments, appendages for movement

Tagmatization : Process which multiple segments form as a group to perform high level function

Redundancy : If injured in one part of body it is okay as it is easy to regenerate parts of the body

Protostomes

Animal whose mouth is formed before the anus

- Spiral cleavage is asymmetrical

- Schizocoely - mesoderm is derived from specific cell early on in cleavage

Deuterostomes

Animal whose anus develops first, then the mouth

- Radial cleavage; equal division in cells results in radial symmetry

- Enterocoely : mesoderm is derived from pouches that branch off developing gut

- Indeterminate cleavage: cell roles are not determined until later

Three main groups of Bilateria

1) Ecdysozoa : Nematodes, Arthropods,

2) Lophotrochozoa : Rotifer, Platyhelminthes, Annelids, Molluscs

3) Deuterostomes : Chordates, Hemichordates, Echinoderms

Which groups in Bilateral are the most related?

Lophotrochozoa and Ecdysozoa

Porifera

Simple sponges

What are the three cell types in Porifera

1) Pinacoytes : Flattened cells on outside of body

2) Archaeocytes : In mesohyl; collagenous matrix and spicules that give form and rigid body

3) Choanocytes : Help water flow into body

What are the three body forms of Porifera

1) Asconoid

2) Syconoid

3) Leuconoid

Asconoid

Sponge Form

Water flows in through the Ostia into spongocoel (central cavity) and then through osculum (where water is expelled)

- Simplest form, size limiting

Syconoid

Sponge Form

Water flows through Ostia into the Radial Chamber (incurrent canals) and then into the spongocoel (central cavity) an then through the osculum (where water is expelled)

- Bigger and more complex than Asconoid

Leuconoid

Sponge Form

Water flows through Ostia into inhalant canal, then into choanocyte chambers, then through exhalant canal, then through the osculum (where water is expelled)

- Does not have real spongocoel

- Choanocytes are in chambers that are dispersed throughout the whole body

How do Porifera feed?

1. Water enters through Ostia

2. Choanoderm spins to cause water movement into sponge

3. Water leaves through osculum

- Filter feeders

Arthropoda - Characteristics

Phylum in the Super-phylum Ecdysozoa

- Metameric segmentation

- Chitinous exoskeleton or cuticle

- Joined limbs on each metamere

- Open circulatory system

Subphylum Chelicerata - What phylum and characteristics

Superphylum Ecdysozoa, phylum arthropoda

- Chelicerae: fangs or jaws

- Two tagmata (parts of body)

- Joined limbs on each metamere

- Open circulatory system

Subphylum Pancrustacea - What phylum and characteristics

Superphylum Ecdysozoa, phylum arthropoda

- Three tagmata; head, thorax, abdomen

What are the two classes in subphylum Pancrustacea ?

1. Malacostraca

2. Insecta

Class Insecta : what phylum and characteristics?

Superphylum Ecdysozoa, phylum arthropoda, subphylum pancrustacea

- 3 tagmata

- Trachae

- Malpigan tubes

Class Malacostraca : what phylum and examples?

Superphylum Ecdysozoa, phylum arthropoda, subphylum pancrustacea

Most of large crustaceans like lobsters

Echinodermata characteristics

- Endoskeleton composed of calcareous ossicles or plates

- Water vascular system

- coelomic

- tube feeders/ ampulla complex

- Complex system of canals

Asteroidea

Class in phylum Echinodermata

- Sea and sun starts

- Radial symmetry; some have bilateral

- Aboral = top of star - Oral = bottom of star

- Have digestive glands and tube feet that run down length of arms

Ophiuroidea

Class in phylum Echinodermata

- Brittle Stars

- Central disk to body

Echinoidea

Class in phylum Echinodermata

- Sea urchins and sea dollars

- Aristotle's lantern - set of ossicles used as skeleton for muscular attachment

- Bilateral symmetry (radial ancestor)

Holothuroidea

Class in phylum Echinodermata

- Sea cucumbers

- Bilateral symmetry

- Soft body

Crinoidea

Class in phylum Echinodermata

- Sea lilies

- Filter feeders

What are the characteristics of the chordates (4)?

1. Dorsal hollow nerve cord - makes up CNS

2. Notochord - humans have as embryo; support structure for dorsal nerve cord

3. Post-anal tail

4. Pharyngeal slits

Subphylum Urochordata

- Sea squirts (sessile filter feeding organism)

- Motile larva form

- Tunic made out of cellulose

- Most related to humans

Subphylum Craniata

subphylum for chordates with heads (brain protected by skull)

- All of the chordates we look at except for the Urochordata

Superclass Agnatha

No jaws

1. Class Myxini - Hagfish

2. Class Petromyzontes - Lampreys

Class Myxini

Class in superclass Agnatha, part of subphylum chordata

- Hagfish

- No jaws

Class Petromyzontes

Class in superclass Agnatha, part of subphylum chordata

- Lampreys

- No jaws

Superclass Gnathostomata

Jaw mouth

1. Class Chondrichthyes - Cartilage fish

2. Class Actinopterygii - Ray finned fish

3. Class Sarcopterygii - Lobe finned fish

4. Class Amphibia - Amphibians

5. Class Mammalia - Mammals

6. Class Reptilia - Reptiles

7. Class Aves - Birds

Class Chondrichthyes

Cartilage fish

- Sharks, skates, rays

Class Actinopterygii

Ray-finned fish

- Trout, bass, salmon

Class Sarcopterygii

Lobe finned fish

- Used to be all fish but tetrapods belong in this group

- Muscular finned fish

Class Amphibia

Amphibians

- Frogs, toads, salamanders

Class Mammalia

Mammals

- Hair and mammary glands

Class Reptilia

Reptiles

- Is a paraphyletic group if it does not contain the aves

- Is a monophyletic group if it does contain the aves

- Crocodiles, lizards, turtles, snakes

Class Aves

Birds