Characteristics of Principle Animal Phyla

Porifera The phylum Porifera includes the sponges Sponges are the simplest of all animals Sponges lack true tissues and organs Sponges are filter feeders. This means that food passes into its open body cavity, specialized collar cells with flagella trap food and pass it to amoebocytes that digest it and carry nutrients to other cells

Porifera Sponges reproduce asexually by budding, however they do have male and female gametes and are capable of sexual reproduction Sponges are very good at regeneration Adult sponges are sessile and do not display symmetry Based on DNA evidence sponges evolved from complex protists There are over 9000 species of sponges

Cnidarians Some of the most common cnidarians are jellyfish, hydra and sea anemones All cnidarians demonstrate radial symmetry, there body parts project from a central axis and have stinking cells Most stinging cells are called cnidocytes they are contained within a capsule One type of capsule is called a nematocyst which contains a single poisonous barb

Cnidarians All cnidarians have a mouth that leads to a gastrovascular cavity. This single structure provides a mechanism for both digestion and distribution of nutrients Cnidarians have very primitive nerve nets that function like simple brains

Cnidarians Cnidarians exist in two different forms at different times of their lives. They either exist as the non-reproductive polyp phase or the reproductive medusa stage (commonly called jellyfish)

What do these have in common?

They are both called Portuguese-Man-O-War

Platyhelminthes Flatworm are a common member of this phylum Flatworms are the simplest form of animals that demonstrate bilateral symmetry Flatworms are the simplest animals to contain all three tissue layers (endoderm, mesoderm, and ectoderm) Flatworms have a digestive tract with a single common opening for food and waste

Platyhelminthes There are over 20,000 species of flatworms Many such as planaria are free-living and non- parasitic Some such as flukes and tapeworms are parasites are parasites both cause severe and lasting damage to their hosts

Platyhelminthes Flatworms are acoelomates – this means that they do not have any body cavities (they are solid)

Nematodes Nematodes are commonly called round worms Roundworms are the first animals to have a complete digestive tract with a mouth and anus Food travels in only one direction (unidirectional) The digestive tract is specialized by region

Nematodes Roundworms are among the most abundant and diverse of all species on Earth Humans are host to at least 50 different species of round worm parasites, such as hookworms, threadworms, and pinworms Trichinosis is caused by eating undercooked pork containing trichinella spiralis

Nematodes Roundworms have a pseudocoelum. This means that they have a fluid filled body cavity in direct contact with the digestive tract

Annelids Annelids are commonly called segmented worms The word annelid means little ring Annelids are the first animals to have a closed circulatory system. This means that the blood remains closed within vessels and wastes diffuse in and out through vessel walls

Annelids Annelids have bilateral symmetry and all three types of body tissue Annelids (and all the advanced animals) contain a coelom. This is large open cavity, completely lined with mesoderm

Acoelomates, Pseudocoelom, and Coelom

Mollusks Mollusks show diverse variations built around a common body form Mollusks include: snails, slugs, oysters, clams, octopi and squid All mollusks have a muscular mass called a foot and a multifunctional structure called a mantle

Mollusks The foot serves in locomotion The mantle is an outgrowth of the body that drapes over the animal. The mantle produces the shell, helps with respiration, waste removal and sensory reception The mantle houses the gills in aquatic mollusks

Mollusks Another body feature unique to mollusks is the the rasping organ called the radula The radula is often used as a type of tooth or drill to smash into the shells of other mollusks All mollusks have a coelom with three open chambers Most mollusks have an open circulatory system that includes a heart that pumps blood into vessels that open into the chambers that are directly bathed by it

Mollusks Diversity in Mollusks - Gastropods - make up the largest group of mollusks - Most have a single spiral shell - Most gastropods live in marine environments. Land snails and slugs live on land

Mollusks Bivalves - Include clams, mussels, oysters and scallops - Bivalves have hinged shells with two halves - They all live in fresh or marine environments

Mollusks Cephalopods (head and foot) - The cephalopods contain the squids and the octupi - They are faster and more agile than either the bivalves or gastropods - Some (like the nautilus) have external shells, most have small internal shells

Bivalves Gastropods Cephalopods

Echinoderms Echinoderms include the sea stars, sea urchins, and sea cucumbers Echinoderms lack body segments and exhibit radial symmetry Echinoderms have a hard internal skeleton called an endoskeleton Echinoderms have a water vascular system that branches into tube-feet used for locomotion, feeding and respiration

Echinoderms Sea stars have a very high capacity for regeneration Sea cucumbers are actually capable of regenerating internal organs Larval echinoderms show bilateral symmetry, yet they have radial symmetry as adults – They start out more advanced and become more primitive

Various echinoderms