animal phyla

Phylum Porifera

•Sessile•Feed by filtering food particles from water that passes through pores in their body

•Sponges•Simplest animals•Lack true tissues and organs•Asymmetrical

Phylum Cnidaria•Jellyfish, Sea Anemone, Coral

•Tentacles with stinging cells

•Sessile or slow-moving

•Tentacles move food into the mouth, then into a digestive sac called the gastrovascular cavity

•Undigested food and wastes exit back through the mouth

•Radial symmetry

Phylum Platyhelminthes

•Flatworms•Mobile•Most are free-living carnivores

-Muscular tube projects through the mouth and sucks in food-Food is then transported to the gastrovascular cavity-Undigested food and wastes exit through the mouth

•But some are parasitic that absorb digested food from inside a host

-Flukes-Tapeworms

Phylum Nematoda•Roundworms

•Complete digestive tract has two openings. a mouth and an anus, at opposite ends of a continuous tube

•Decomposers, parasitic, or free-living

•Human parasitic examples: pinworm & hookworm

Phylum Annelida-segmented worms (earthworms, leeches)

-longitudinal and circular muscle fibers surrounding body wall

-closed circulatory system: blood remains contained within vessels

Phylum Mollusca

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

Phylum Mollusca AnatomyFoot – muscular mass of tissue that functions in locomotion (video clip)

Mantle – outgrowth of body surface that drapes over the animal – produces the shell in certain mollusks – functions in respiration, waste disposal, and sensory reception

Mollusks have an open circulatory system

– a heart pumps blood into vessels– the vessels open into chambers where the organs are bathed in blood

Phylum Echinodermata-sea urchins, sea stars, sea cucumbers

-spines and plates under the skin make up the endoskeleton (but with no central spine)

-the water vascular system is a network of water-filled canals that aid movement

-tube feet function in locomotion, feeding, and respiration

Phylum ArthropodaMost numerous and diverse animals

•75% of animals belong to this phylum•global population is 1 billion billion (1018)

1. crustaceans (lobsters, crabs, shrimp)2. arachnids (spiders, scorpions, mites, ticks)3. insects4. centipedes and millipedes

General Characteristics of Phylum Arthropoda

Segmented body (different segments):• head – sensory antennae, eyes, mouthparts• thorax – midsection that bears jointed

appendages• abdomen – houses digestive and reproductive

organs

General Characteristics of Phylum Arthropoda

-open circulatory system with a copper-based blood called hemolyph-unlike humans, arthropod blood does not carry oxygen

General Characteristics of Phylum ArthropodaHow do arthropods get oxygen to their tissues?

Aquatic arthropods have gills

Terrestrial arthropods have trachea – a system of air tubes

Exoskeleton – external skeleton that consists of proteins

mixed with chitin

– protection, avoid dehydration

Must molt periodically

General Characteristics of Phylum Arthropoda

CrustaceansHead and thorax is fused cephalothoraxHave antennae; mostly aquatic

Copepods play an enormous role in the food chain of marine and freshwater communities

ArachnidsHead and thorax is fused cephalothoraxNo antennae; mostly terrestrial

Two pairs of mouthparts:

1. Fanglike mouthparts used to paralyze prey with poison

2. Mouthparts used to manipulate prey once it is paralyzed

Insects – the most successful arthropods

Entomology – study of insects

Reasons for success:

-ability to fly-diverse feeding habits-ability to metamorphasize

Many arthropods, including insects, have compound eyes

Compound eyes consist of many eyes (can be over 1,000!)

Excellent in detecting motion, however, poor image resolution

MetamorphosisMetamorphosis – a process in which body form changes from the sexually immature to the sexually mature stage

Incomplete metamorphosis:

-change is not dramatic-molting causes insect to grow

Complete metamorphosis:

-larval stage function in eating and growing-adult stage functions in moving and reproducing

Phylum Chordata

Notochord – flexible rod that extends down the length of the body

Invertebrate chordates – notochord becomes skeletonVertebrate chordates – notochord disintegrates

Chordates are named after a structure that is found in all chordate embryos