FNR 201 Exam 2(Ch 6.3-8.2)

Characteristics of Animals

Characteristics of Animals

Multicellular
Eukaryotic w/out cell wall
Motile
Invertebrates & Vertebrates

Phylum Porifera (sponges)

Asymmetrical
Sessile, no tissues/organs
Color=drab or bright

Sponges: Structure

Built around water canals
Lack tissues
Need structural materials to maintain shape & function(spongin, spicules)

Ostia(ostium)

tiny pores in sponge 's body that circulate water and bring in nutrients & O2

Spongocoel

spacious cavity of sponge

Osculum

Large opening through which water exits the sponge which carries away waste

Choanocyte

Have flagella that forces water to circulate in the sponge

Pinacocytes

Cells in the outer covering that do not have flagella

Archaeocytes

Can assume any cell form
Important for repair & regeneration
Transports food & other materials

Spongin

flexible support protein for sponges

Spicules

Skeletal elements for sponge's support
Produced by specialized cells
composed of silica

Sponge Shape: Asconoid

Simplest
Tubular, always small & found in clusters

Sponge Shape: Syconoid

1st stages of body wall folding
Folded 'pockets' lined with collar cells

Sponge Shape: Leuconoid

Most complex & highest degree of folding
Many chambers(osculum) & reduced spongocoel

Sponges: Nutrition & Digestion

suspension/filter feeders
Choanocytes trap small food particles
Pinacocytes & Archeocytes engulf large food particles
Archeocytes do the most digestion

Sponges: Asexual Reproduction

Budding: uncommon, bud drops of 'parent' & forms new sponge
Fragmentation: New sponge from broken pieces

Sponges: Sexual Reproduction

Most are hermaphrodites
Eggs develop from archeocytes
Sperm develop from modified choanocytes
Males broadcast sperm externally
Sperm fertilize eggs internally

Ecological Role of Sponges

Competition for space
Spicules & chemical deterrents for predators
Mutualists & commensals: many organisms live inside sponges

Phylum Cnidaria

Jellyfish, sea anemones, corals
Radial symmetry
Specialized sting cells called cnidocytes

Cnidocytes

Occur on tentacles

Cnida

Stinging organelle within cnidocyte
Used for prey capture, defense & locomotion

Nematocyst

Spear-type cnidae
Most common

Cnidocil

trigger that discharges nematocyst
Triggered by contact
Can also be triggered by chemicals

Polyp stage

Benthic with cylindrical body
E.g. Corals & sea anemones

Medusa stage

Free-floating stage
Many have both stages in life cycle
E.g. Jellyfish

Class: Hydrozoa

Hydras and Portuguese man-of-war
Both polyp & medusa stage
Physically connected to each other(colonial)
Feeding polyp
Reproductive polyp

Class: Scyphozoa

True jellyfish
Generally polyp & medusa (prominent) stage
Most small some giant
Most float with currents, some are strong swimmers
Have Photoreceptors
Sense light & dark

Class: Anthrozoa

Sea anemones and corals
Only have a polyp stage
sessile(corals) or sedentary (anemones)

Sea anemones:

Polyps more complex than hydrozoans
Can expand, retract & extend tentacles
Can move locations

Corals

Polyps secrete skeleton that may be hard or soft
Hard corals skeleton made from calcium carbonate
Soft corals include sea fans & sea pens

Hard Corals(Order: Scleractinia)

Form large colonies of small polyps
All polyps connected by horizontal sheet of tissue
Form reefs
Have mutualistic symbiosis with zooxanthellae

Soft Corals(Order: Alcyonacea)

Most resemble plant-like forms, e.g. Sea Fans
Octocorals: 8 feathery tentacles instead of 12
Gorgonians: most common octocoral

Cnidarians: Nutrition

Digest food in central gastrovascular cavity
Waste forced back out mouth

Hydrozoans & Corals: Nutrition

Filter feed mainly on plankton

Jellyfish: Nutrition

Some are carnivores of invertebrates & fish

Anemones & Some Corals: Nutrition

Feed on invertebrates & small fish
Paralyze prey with nematocysts

Hydrozoans: Reproduction

Asexual polyp stage and sexual medusa stage
Polyps form buds
Buds turn into medusa
Adult medusa release gametes
Gametes join to form planula larvae
Larvae are planktonic
Larvae disperse, grow & settle to form polyp

Jellyfish: Reproduction

Asexual polyp stage and sexual medusa stage
Process very similar to hydrozoans
Structure of polyp and budding different to hydrozoans

Corals & Anemones: Asexual Reproduction

Asexual reproduction common(for anemones)
Budding: large colonies of identical hard corals
Fission: anemone splits in two & each half grows into new individual
Pedal laceration: parts of pedal disk (base) left behind to grow into new animals

Corals & Anemones: Sexual Reproduction

Corals can have male & female forms
Gametes released & merge to form larvae
Planulae larva disperse & settle

Phylum: Ctenophora

Comb jellies
Planktonic & almost transparent
Radial symmetry
Lack stinging cells
8 rows of comb plates (ctenes)
Ctenes comprised of large cilia for locomotion
Bioluminescent

Bilateral Symmetry

Only 1 plane through mid-line of central axis divides animal into similar right & left halves
Streamlined body shape = increasing mobility
Cephalization

Cephalization

Concentration of sense organs at one end of animal

Phylum: Platyhelminthes

Bilateral symmetry & cephalization
Class: Tubellaria
-Free-living
Class: Trematoda
-Parasitic flukes
Class: Cestoda
-Parasitic tapeworms

Tubellarians

Many pelagic , some benthic
Important members of meiofauna
Sensory receptors in head region
Detect light, chemicals, movement etc.
Funnel nutrients to higher trophic levels

Trematodes

Complex life cycles
3+ stages - use snail as intermediate host
Can lower fitness of host population

Cestodes

Live in host's digestive tract
Can lower fitness of host population

Phylum: Mollusca

soft bodied animals
clams, octopus, snails, squid
Diverse & successful
Most covered with Calcium carbonate shell
Wide range of sizes & lifestyles

Molluscan Body

head, muscular foot, and visceral mass of internal organs

Molluscan Body: Mantle

Protective tissue covering soft body
Secretes the shell but is not the shell

Molluscan Body: Radula

Ribbon of tissue containing teeth
Occurs in all mollusks except bivalves
Many adaptations
Scrape, pierce, tear, & cut food

Molluscan Shell: Periostracum

Outer most layer
Composed of proteins that protect the shell from dissolution and boring organisms

Molluscan Shell: Prismatic Layer:

Middle layer
Composed of Calcium Carbonate
Makes up majority of the shell

Molluscan Shell: Nacreous Layer

Innermost layer
Calcium Carbonate, but different crystal structure and found in thin sheets

Mollusca: Chitins

Class: Polyplacophora
8 overlapping plates formed from mantle
Flattened bodies &
large, flat foot to attach firmly to rocks
Found in intertidal zones
Scrape algae & other organisms from rocks

Mollusca: Gastropods

Class: Gastropoda
"stomach foot"
Largest group of molluscs
Most have 1-piece shells
Shells can be coiled or uncoiled
Operculum : Covering over aperture
-allows shell to close
-made from CaCO3 or stiff protein

Mollusca: Nudibranch

Class: Gastropoda
"naked gill"
Marine gastropods lacking shell
Cerata : projections from body to increase gas exchange
Some feed on cnidarians
& incorporate cnidocytes into tips of cerata for defense
Bright colors warn of toxicity

Gastropod Nutrition

Herbivores use radula to graze on microalgae
Carnivores locate prey using chemical trail
-usually extend proboscis to search
-some have modified radula as spears
Scavengers & deposit feeders
Filter feeders use ciliary action
-trap food particles with gills

Gastropod Reproduction

Most species have separate sexes
-internal fertilization
Two types of free-swimming larva:
-trochophore, veliger
Some species hermaphrodites:
-oysters, scallops, shipworms

Trochophore

Stage of primitive gastropods that shed their eggs into the water

Veliger

Most common of marine species
Can travel great distances to aid in the dispersal of the species

Mollusca: Bivalves

Class: Bivalva
Specialized filter feeders
No head or radula
Lateral compressed body
Two shell halves attached dorsally
Hinged by ligaments
Abductor muscles: large muscles that close shell
Incurrent & excurrent siphons: respiration & feeding

Bivalve Habitat and Ecology

Burrowing infauna:
-have siphons (e.g. clams)
Attached surface dwellers -fusion/byssus (e.g mussel)
Non-attached surface dwellers
-jet propulsion (e.g. scallops)

Mollusca: Cephalopoda

Nautili, Squids, and Octopods
Foot modified into head-like structure
Ring of tentacles project from head
Lack shells or have internal shells
Fast swimming predators
Well developed, complex nervous system
Radula and beak-like jaws to crush or rip prey

Cephalopods: Nautilidae

Chambers separated by septa
-chambers filled with gas to aid buoyancy & swimming
Head with 60-90 tentacles
Food first stored in crop, then sent to stomach for digestion

Nautilus Ecology

Propel themselves with jet propulsion
Water drawn in through incurrent siphon
Water expelled through excurrent siphon
Demersal; during day, rise to surface at night
Primarily feed on benthic prey
Eat hermit crabs & scavenge detritus

Cephalopods: Coleoids

Cuttlefish, Squids, Octopus
8-10 appendages with suckers
Sepia: Inky fluid dispelled through excurrent siphon
Locomotion via jet propulsion or fin undulation
Most advanced & complex nervous system among invertebrates

Coleoids: Cuttlefish

bulky body & fins
10 appendages
8 arms & 2tentacles
Small internal shells
Some shells have chambers
Shell is embedded in mantle

Coleoids: Squid

Paired fins derived from the mantle
8 arms and 2 tentacles, in 5 pairs
Cup-shaped suckers attached by stalk
Suckers only on flat inner surface of arm
"Teeth" around the rim of each sucker
Pen : Small, degenerate shell

Coleoids: Octopus

Sac-like bodies without fins
Lack internal shell
8 arms with suckers (no tentacles )
Suckers lack stalks & teeth
Not as good swimmers as cuttlefish & squids

Cephalopods Color and Shape

Communicate through movement of arms/body & color changes
Chromatophores:
-dark color: granules dispersed
-light color: granules concentrated
Effects:
General body color changes
Also stripes & rings
Purpose:
Warnings to predators
Camouflage

Phylum: Annelida

Segmented Worms
Most are infauna
Segments increase mobility
Hydrostatic skeleton
-fluid (water) supports body structure
Parapodia
-paired appendages on each segment
Setae (small bristles): On skin
-locomotion, digging, etc.

Annelids: Polychaetes (errant)

Actively move
Pelagic, burrowing, tube-dwelling etc.
Can have large jaws to capture prey

Annelids: Polychaetes (sedentary)

Sessile
Create burrows or tubes from a variety of materials
-e.g. Sand, protein, CaCO3
Rings of ciliated tentacles extend from tube
-e.g. Christmas tree worms

Polychaeta Nutrition

Mostly active at night
Tube-dwellers:
-partially or completely leave tube to feed
Suspension feeders:
-most sedentary
-use special feeding structures
Deposit feeders:
-non-selective & selective

Selective Deposit Feeders

Seperate organic & mineral particles first
Ingest only organic matter
Some use mucus-covered tentacles
E.g. spaghetti worm

Non-selective Deposit Feeder

Ingest both organic & mineral particles
Digest organic material (e.g. bacteria)
Remaining minerals expelled as fecal casts
E.g. lugworm

Phylum: Nematoda

Round Worm
80% of all animals on earth are nematodes
Round, slender & elongate bodies
Scavengers, some parasitic
Most hermaphrodites, but some have separate sexes

Ecological Role of Marine Worms

Nutrient cycling
Predator-prey relationship
-important link in food web
Symbiotic relationships:
-parasitism, commensalism

Phylum: Arthropoda

Jointed appendages
Exoskeleton comprised of protein & chitin
Molting to shed and replace exoskeleton
Body divided into head, thorax, abdomen

Arthropods: Chelicerates

Primitive group
Lack mouth parts but have oral appendages (chelicerae)
6 pairs of appendages
-e.g. spiders, scorpions, horseshoe crabs, sea spiders

Arthropods: Mandibulates

Mandibles : Pairs of appendages on head
used for feeding
Most mandibulates are crustaceans
Range from zooplankton to lobsters

Mandibulata: Crustaceans

Head, thorax, & abdomen
2 pairs of sensory antennae, mandibles, maxillae, walking legs
Modified legs include:
Swimmerets: swimming legs
Chelipeds: defense

Crustacean Molting

Crucial for growth
Animal becomes vulnerable & hides
Old animals may cease molting
Driven by hormones produced in head
Altered by environmental changes

Decapod Crustaceans

Class: Malacostraca
5 pairs of walking legs
First pair of legs modified to chelipeds
Pincers used for prey capture & defense
Most decapods are small
Many specialized adaptations & behaviors
-e.g. Hermit crab; swimmer crab

Reproduction of Decapod Crustaceans

Sexes usually separate & use internal fertilization
Most females brood eggs
Use brood chambers or modified appendages
Eggs hatch into pelagic larvae
Subsequent molts of larvae eventually lead to adult form

Malacostraca Species: Mantis Shrimp

Order: Stomatopoda
Highly specialized predators
Most are tropical
Live in crevices & burrows
Modified second pair of thoracic appendages
Enlarged & movable finger
Spearers: impale soft prey
Smashers: crush hard prey

Malacostraca Species: Krill

Order: Euphausiacea
Pelagic, shrimp-like
Filter feeders of zooplankton
Most krill bioluminescent
Photophore: specialized light organ
Often form huge swarms
Densities up to 60,000 per cubic meter

Crustacea: Copepods

Class: Copepoda
Largest group of small crustaceans
Undertake vertical migrations by sensing light
Most are filter feeders of phytoplankton
Males adhere to females to transfer spermatophores
Some are parasitic

Crustacea: Barnacles

Class: Cirripedia
Only sessile crustaceans
Attach to rocks, floating debris, boats etc.
Also attach to animals (e.g. turtles, whales)
Enclosed in CaCO3 shell
-shell attached directly or via stalk
Cirripeds : Feathery appendages extend from shell to filter feed

Ecological Roles of Arthropods

Important food source for many animals
Symbionts: cleaner shrimp
Recycling & Fouling: feed on detritus & help recycle nutrients
barnacles=fouling problem

Phylum: Echinodermata

Sea/brittle stars, sea urchins & sea cucumbers
Bilateral symmetry & modified radial symmetry
Larval stages bilateral, adult radial
Mostly benthic & found at almost all depths
Tube feet for locomotion & grabbing food

Echinoderm Structure

Endoskeleton just beneath dermis
Ossicles: plates of CaCO3
Spines & tubercles extend out from ossicles
Madreporite for water entry
No brain

Echinoderm: Sea Stars

Class: Asteroidea
Central disc with 5 arms
Ambulacral grooves on underside with tube feet that radiate out from mouth along each ray
Frequently rough or spiny

Sea Star Regeneration

Sea stars can regenerate arms
Or discard arms that is injured/damaged
Some can regenerate whole new body
From just a small portion of central disc & 1 arm

Echinoderm: Brittle, Basket, and Serpent Stars

Class: Ophluroidea
Greatest species diversity of echinoderms
5 slender arms frequently covered with spines
Tube feet lack suckers
Used for locomotion & feeding
Ability to autonomize

Ophluroidean Feeding

Brittle stars: Filter feed by waving arms in water
Basket stars: Filter feed by fanning complex arms
Deposit feeders: Gather organic particles from bottom
-use tube feet to gather into food boils
-pass food balls to mouth

Echinoderms: Sea Urchins

Class: Echinoidea
Test: Hard exoskeleton that encloses body
Benthic on sand or hard surfaces
Have movable spines
Regular (radial): Spherical body with long spines (E.g. sea urchins)
Irregular (bilateral): Not spherical & have short spines (E.g. sand dollar)

Regular Echinoid Feeding

Mostly grazers that scrape algae from surface
Aristotle's lantern: chewing structure composed of 5 'teeth'
Graze on macro-algae (e.g. kelp)

Irregular Echinoid Feeding

Most are selective deposit feeders
Some are filter feeders (e.g. sand dollars)