Biology II Unit 3

Animals

multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

T/F: All animals ingest their food.

True

Unique, defining tissue characteristics of animals:

Nervous and muscle tissue

Most animal reproduction:

Sexual reproduction

Dominant stage in animal life cycle

Diploid

Rapid cell division

Cleavage

Cleavage leads to formation of:

Multicellular, hollow, blastula

Blastula undergoes gastrulation and forms:

Gastrula (multi-layered)

Most animals have at least one…

Larval stage

Larva undergoes __ to become a juvenile.

Metamorphosis

Juvenile

Resembles adult, not sexually mature

Set of morphological and developmental traits

Body plan

Radial symmetry

Have a top and bottom, but no sides

Bilateral symmetry

Has dorsal and ventral, anterior and posterior, & left and right sides (split down middle)

Radial animals are often…

Sedentary

Bilateral animals’ movement

Active with central nervous system

How many germ layers in development of tissues and organs in embryo

3

Ectoderm

germ layer covering the embryo's surface, outer

Endoderm

lines the developing digestive tube (archenteron), innermost germ layer

Diploblastic animals

Only have ectoderm and endoderm

Triploblastic animals

Have ectoderm, endoderm, and mesoderm

All bilaterally symmetrical animals are… (germ)

Triploblastic

Most triploblastic animals posses a…

Body cavity

Coelom

True body cavity, derived from

mesoderm

Coelomates

Animals that possess a true coelom

Pseudocoelom

Body cavity derived from mesoderm and endoderm

Pseudocoelomates

Triploblastic animals that possess a pseudocoelom

Acoelomates

Triploblastic animals that lack a body cavity

Functions of a body cavity:

• Fluid cushions suspended organs

• Fluid acts like a skeleton against which muscles can work

• Enables internal organs to grow and move independently of the outer body wall

Blastospore

Forms during gastrulation, connects the archenteron to the exterior of the gastrula

Protostome development:

Blastopore becomes the mouth

Deuterostome development:

Blastopore becomes the anus

What percentage of known animals are invertabrates?

95%

Phylum porifera

Sponges

Filter feeders

Capture food particles suspended in the water that passes through their body (sponges, some sharks)

Spongocoel

Water drawn into sponge, “mouth”

Osculum

Water moves out of sponge, “anus”

T/F: Sponges have tissues.

False, they have groups of similar cells that act as functional units

Choanocytes

Sponge cells - Flagellated collar cells, generate a water current through the sponge and ingest suspended food

Mesohyl

Sponge tissue - gelatinous, noncellular layer between 2 cell layers

Amoebocytes

Sponge cells - differentiating cells found in mesohyl, play roles in digestion and manufacture of skeletal fibers

Reproduction of sponges:

Hermaphroditism, each individual functions as both male and female

Sequential hermaphroditism

Function first as one sex, then another - sponges

Cniderians include

Jellies, corals, and hydras

Cniderian body plan

simple diploblastic, radial body plan

Basic body plan of Cniderian

sac with a central digestive compartment (gastrovascular cavity), single opening functions as mouth and anus, can be polyp or medusa

Polyp

Sessile, adheres to substrate by the aboral end (mouth facing up) of its body

Medusa

Bell-shaped body, mouth on underside (jellyfish)

T/F: Cniderians are carnivores.

True, use tentacles to capture prey

Cnidocytes

Tentacles are armed with, unique cells, function in defense and capture of prey

Nematocysts

Specialized organelles within cnidocytes that eject a stinging thread

Clades of phylum Cnideria

Medusazoa and Anthozoa

3 groups of Medusazoans:

* Scyphozoans (jellies)
* Cubozoans (box jellies)
* Hydrozoans (alternate between polyp and medusa)

Hydra

Medusazoan, only found in polyp form (outlier), reproduces asexually (budding)

Anthozoans include:

Corals and sea anemones

Anthozoans occur only as…

Polyps

Bilaterian animals

Bilateral symmetry, triploblastic development

Clade Bilateria contains:

Lophotrochozoa, Ecdysozoa, and Deuterostomia

Lophotrocozoa includes:

Flatworms, rotifers and acanthocephalans, ectoprocts, brachiopods, molluscs, and annelids

Platyhelminthes

Flatworms, acoelomates, (flukes, tapeworms, planarian, etc)

Protonephridia

Flatworm excretory apparatus, “kidney”

2 lineages of flatworms:

Catenulida (“chain living,” budding, free living) and Rhabditophora (diverse, include free living and parasitic)

Planarians

Rhabditophorans, have light sensitive eye spots and nerve nets

2 important groups of parasitic Rhabditophorans

Trematodes (flukes, snail hosts) and tapeworms (eggs spread through feces)

Scolex

Tapeworms, contains suckers and hooks

Proglogttids

Tapeworms, units that contain sex organs and form a ribbon behind the scolex

Rotifers - unusual reproduction:

Some species lack males entirely

Acanthocephalans

“Spiny-headed worms,” group of highly modified “rotifers”

Ectoprocts

“Bryozoans,” sessile, resemble clumps of moss

Brachiopods

Resemble clams (valves open opposite), attach to sea floor by a stalk

Molluscs

Snails and slugs, oysters and clams, and octopuses and squids; calcium carbonate shell

Mollusc body plan (3 main parts)

• Muscular foot (movement)

• Visceral mass

• Mantle (covering, inner most part of shell)

Radula

Strap-like, how molluscs feed (tongue-like)

4 major clades of molluscs:

• Polyplacophora (chitons)

• Gastropoda “stomach foot” (snails and slugs)

• Bivalvia (clams, oysters, etc)

• Cephalopoda “head foot” (squids, octopuses, cuttlefish, and chambered nautiluses)

Chitons

Oval shaped, marine, 8 dorsal plates, use foot as suction cup and radula to scrape algae

75% of molluscs are:

Gastropods

Gastropods

Movement by rippling cilia, single spiraled shell

Adductor muscles

Hold hinge (bivalves)

T/F: Some bivalves have eyes and sensory tentacles along the edge of their mantle.

True

The mantle cavity of a bivalve contains…

Gills (for feeding and gas exchange)

Cephalopods

Active marine predators \n with beak-like jaws surrounded by tentacles

Cephalods immobilize prey with

Poison in their saliva

Cephalopod muscular excurrent siphon (part of tentacles) is…

A modified foot

Chambered nautilus

Only cephalopod with a shell

Cephalopods are the ____ (most complex)

“Humans of the sea”

Molluscs have the most documented __

Extinctions

Molluscs are threatened by:

Habitat loss, pollution, non-native species, and over harvesting by humans

Annelids

Coelomates, bodies composed of a series of fused rings

3 classes of phylum annelida:

* Polychaeta (polychaetes)
* Oligochaeta (oligochaetes)
* Hirudinea (leeches)

Polychaeta

Have paddle/ridge-like structures called parapodia, Each parapodium has numerous chaetae (bristles made of chitin)

Oligochaetas

Earthworms, elaborate gills/tentacles used for filter feeding

Chemical that prevents blood from coagulating (secreted by leeches)

Hirudin

Ecdysozoans

Covered by tough cuticle

2 largest phyla of ecdysozoans:

Nematodes and arthropods

Nematodes

Roundworms, lack circulatory system, contain alimentary canal

Trichenella spiralis

Roundworm, acquired by humans through uncooked pork, nematode

Caenorhabditis elegans

Roundworm, model research organism, soil nematode

2/3 species of known animals are:

Arthropods

Arthropod body plan:

Consists of a segmented body, hard exoskeleton, and jointed appendages

Ecdysis

Molting of exoskeleton