Animal Biology test 2

characteristics of the phylum cnidaria

1\.Entirely aquatic, some in fresh water but mostly marine

2\.Radial Symmetry or biradial symmetry around a longitudinal axis with oral and aboral ends; no definite head

3\.Two basic types of individuals: polyps and medusae

4\.Exoskeleton or endoskeleton of chitinous, calcareous or protein components in some

5\.Body with two layers, epidermis and gastrodermis with mesoglea; mesoglea with cells and connective tissue in some

6\.Gastrovascular cavity with a single opening that serves as both mouth and anus; extensible tentacles usually encircling the mouth or oral region

7\.Special stinging cell organelles called nematocysts in either epidermis or gastrodermis or both, nematocysts abundant on tentacles, where they form batteries or rings

8\.Nerve Net with symmetrical and assymetrical synapses; with some sensory organs; diffuse conduction

9\.  Muscular system of an outer layer of longitudinal fibers at the base of the epidermis and an inner one of circular fibers at the base of the gastrodermis

10\. Asexual reproduction by budding (in Polyps) or sexual reproduction by gametes; sexual forms monoecious or dioecious, planula larvae

11\. No excretory or respiratory system

12\. No coelomic cavity

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structure of an Anemone

what are Cnidarians

an ancient phylum of Eumetazoans; one of the oldest groups in this clade

All animals except ________ belong to the clade Eumetazoa, animals with true tissues

sponges and a few other groups

Cnidarians have diversified into a wide range pf both sessile and motile forms including…

jellies, corals and hydras

what do Cnidarians exhibit?

a relatively simple diploblastic, radial body plan

the basic body plan of a cnidarian is…

a sac with a central digestive compartment, the gastrovascular cavity; a single opening functions as mouth and anus

what are the two variations for cnidarians body plan?

the sessile polyp and motile medusa

picture of a polp and a medusa

cnidarians are carnivores that use…

tentacles to capture prey

what are cnidarians tentacles armed with?

cnidocytes- unique cells that function in defense and capture of prey

what are nematocysts?

specialized organelles within cnidocytes that eject a stinging thread

a cnidocyte that contains a stringing capsule, a nematocyst, which contains a coiled thread

name the four major classes of the Phylum Cnidaria

Hydrozoa, Scyphozoan, Cubozoan, and Anthozoa

main characteristics of Hydrozoa (Portuguese man of war, hydras, Obelia, some corals)

most marine, a few freshwater; both poly and medusa stages in most species; polyp stage often colonial

Scyphozoan ( Jellies, sea nettles)

all marine; polyp stge absent or reduced free swimming medusae up to 2M in diameter

cubozoan( box jellies, sea wasps)

all marine; box-shaped medusae; complex eyes; potent venom

anthozoa( sea anemones, most corals, sea fans)

all marine; medusa stage completely absent; most sessile; many colonial

life cycle of the hydrozoan Obelia

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Cnidarian body wall

integument Cnidaria

tentacles lined with nematocysts

skeleton Cnidaria

hydrostatic skeleton- water or body fluids confined in a cavity of the body and against which elements of the body wall act

movement(muscularity) Cnidaria

depends on the stage of the life cycle, polpys-sessile, medusae-free swimming

digestion Cnidaria

Nematocysts lining the tentacles bring in foods to the gastrovascular cavity where digestion occurs

nervous(control) Cnidaria

nerve net

protection Cnidaria

stringing cells that line the tentacles

generalized Cnidarian life cycle

Obelia structure and life cycle

structure of gonionemus medusa

structure of scyphozoan medusa

aurelia life history

coral reef ecosystem

coral bleaching

platyhelminthes characteristics

1\.Triploblastic – (3 germ layers)

2\.Bilaterally symmetrical; definite polarity of anterior and posterior ends; Somewhat Cephalized

3\.Body flattened dorsoventrally; oral and genital apertures mostly on ventral surface

4\.Body with multiple reproductive units in one class

5\.Epidermis may be cellular or synctial (a mass of protoplasm containing many nuclei and not divided into cells)

6\.Muscular system in the form of a sheath of circular, longitudinal and oblique layers beneath the epidermis or tegument 7. No internal body space other than digestive tube; spaces filled with parenchyma (Cestodes lack digestive tube) 8. Digestive system incomplete (gastrovascular type); absent in some

Nervous system with a pair of anterior ganglia with longitudinal nerve cords connected by transverse nerves

10\. Simple sense organs; eyespots in some

11\. Excretory system of two lateral canals with branches bearing flame cells (Protonephridia as excretory/osmoregulatory structures); lacking in some forms

12\. Respiratory, circulatory and skeletal systems lacking, lymph channels with free cells in some nematodes. Most forms monoecious; complex reproductive system with well developed gonads, ducts and accessory organs; internal fertilization; life cycle variable

14\. Class Turbellaria mostly free- living; Classes Monogenea, Trematoda, and Cestoda entirely parasitic

flatworms

\*Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats

\*Although flatworms undergo triploblastic development, they are acoelomates

\*They are flattened dorsoventrally and have a gastrovascular cavity

\*Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance

what are the four classes of flatworms?

\*Turbellaria (mostly free-living flatworms)

\*Monogenea (monogeneans)

\*Trematoda (trematodes, or flukes)

\*Cestoda (tapeworms)

turbellarians

\*are nearly all free-living and mostly marine

\*The best-known turbellarians are commonly called planarians

planarians characteristics

\*Planarians have light-sensitive eyespots and centralised nerve nets

\*The planarian nervous system is more complex and centralised than the nerve nets of cnidarians

\*Planarians are hermaphrodites and can reproduce sexually, or asexually through fission

monogeneans and trematodes

\*live as parasites in or on other animals

\*They parasitise a wide range of hosts, and most have complex life cycles with alternating sexual and asexual stages

\*Trematodes that parasitise humans spend part of their lives in snail hosts

Most monogeneans are parasites of fish

life cycle of a blood fluke

tapeworms

\*parasites of vertebrates and lack a digestive system

\*Tapeworms absorb nutrients from the host’s intestine

\*Fertilised eggs, produced by sexual reproduction, leave the host’s body in faeces

integument Platyhelminthes

\*Epidermis in contact with the environment

\*Tegument is highly efficient at absorbing nutrients and is effective for protection

skeleton Platyhelminthes

none to speak of, a few have structures for holding on

movement(muscularity) Platyhelminthes

well developed muscularity

digestion Platyhelminthes

\*Digestion is variable

\*Pharynx of turballarian serve as mouth and anus

\*Digestive tracts are of varying complexities

nervous (control) Platyhelminthes

\*Variable

\*Relatively well developed with a cerebral ganglia and a nerve cord in planaria

nervous system in turbellarians

circulation Platyhelminthes

highly centralized digestive system in contact with cells that diffuse nutrients

protection platyhelminthes

some have a scolex for holding on, photoreceptors in free-living platyhelminths

respiration platyhelminthes

diffusion through the tegument

waste removal Platyhelminthes

protonephridia, flame cells

reproduction Platyhelminthes

\*Highly variable, but possibly the most interesting system in the Entire Phylum

\*Hermaphroditic

turbellarian reproductive system

asexual reproduction in turbellarians

pseudocoelomate body plan

rotifera, kinorhncha, nematoda, nematomorpha, acanthomorpha, lricifera, priapulida

external anatomy of a an adult kinorhynch

what is the highest percent of nematoda species

arthropoda

nematoda characteristics

Triploblastic, bilateral, vermiform (resembling a worm in shape; long and slender), unsegmented, pseudocoelomate
2\. Body round in cross section and covered by a lateral cuticle; molting usually accompanies growth in juveniles
3\. Complete digestive tract; mouth usually surrounded by lips bearing some sense organs
4\. Most with unique excretory system comprised of one or two rennete cells or a set of collecting tubules
5\. Body wall has only longitudinal muscles

pseudocoelomate structure

ectoderm, mesoderm, endoderm

two major classes of pseudocoelomate

secernentea(phasmidea)- phasmids in the tail

adenophorea(aphasmidia)- phasmids absent

integument nematoda

Collagenous cuticle, three layers cortex, matrix, and basal layer

Molt four times before maturation

skeleton nematoda

hydrostatic skeleton consisting of an internal fluid filled pseudocoel

movement(muscularity) nematoda

bLongitudinal muscles and circular muscles to allow for characteristic undulating movement

nervous(control) nematoda

relatively complex nerve ring

protection Nematoda

Movement, teeth in some, and sheer numbers in reproduction help to protect perpetuation

nematoda mouth

respiration nematoda

diffusion from the cuticle

waste removal Nematoda

renette cells responsible for osmoregulation

renette cells

reproduction Nematoda

Definitely dioecious

Internally much different and externally males with “curl” 

Usually females larger than males, but not always

Phylum Mollusca

soft bodied, shelled-some without, cephalization- sensory organs, mouths, body divisions- visceral mass, head-foot, mantle, complete digestive tract, digestive glands, specialized feeding structures, circulatory system-heart (2 chambers), open system in most groups, closed in cephalopods, coelom restricted to pericardium in most cases

banana slug

scallops

integument bivlaves

soft bodied, hard 2 part shell

integument gastropods

soft bodied, often a shell with torsion

integument cephalopods

soft bodied with tentacles and feet, some with a hard shell

mussels

skeleton bivalves

hydrostatic skeleton inside a two part shell

skeleton gastropods

hydrostatic skeleton inside a one part shell usually

skeleton cephalopods

hydrodtatic dskeleton inside a one part shell(if any), some skeletal elements( beak, pen)

generalized mollusc anatomy

respiration mollusc

gills

mollusc reproduction and development

indirect development- larval stages, trochophore larva-free swimming, ciliated, shell formation begins, veliger larva- free swimming, ciliated velium forms, shell/body torsion occurs, spat- metamorphic form between veliger and juvenile, shell elaborates

marine gastropods

cowries

pulmonata

the mantle cavity serves as a lung, glandular epidermis-secrete mucus upon which gastropod glides

metabolism(digestion) bivalves

complete digestive system coordinating with the circulatory system; typically filter feeders

metabolism(digestion) gastropods

complete digestive system also with unusual anal opening leading to fouling

metabolism(digestion) cephalopods

complete digestive system with ceca that are accessory as well as highly developed digestive glands

largest cephalopods?

squid

nervous(control) system bivalves

relatively well developed in some many sensory eyes around the fringe of the mantle

nervous(control) system gastropods

well developed nervous system with stalked eyes that can move in all directions

nervous(control) system cephalopods

very well developed nervous system, problem solving brains

cephalopod eye

circulation bivalves

open circulation with blood connected to pools or sinuses for movement of materials

circulation gastropods

open circulatory system

circulation cephalopods

open circulatory system with hearts for directing blood from gills and throughout the body to sinuses

protection bivalves

hard shell, varied styles of locomotion, glochidia larvae

protection gastropods

hard shell often with an operculum, many poisonous

protection cephalopods

some with a shell, hard, bird-like beak, suckers, ink sac for diversionary tactics

reproduction bivalves

•Entirely aquatic with sexual reproduction, gametes are released into the water for external fertilization