Chap. 33 Flashcards
Animals in the phylum Porifera are known informally as …….
sponges
-they are filter feeders
how do sponges eat
Water is drawn through the pores into a central cavity, the spongocoel, and then flows out of the sponge through a larger opening called the osculum.
Porifera info list
Common name, Symmetry, Germ layers, Nerves system, feeding syst., gas exchange, circulation, reproduction
Primarily Marine; sessile (only larva motile)
* Common name: Sponges
* Germ layers: no true tissues
* Body cavity: no cavity
* Symmetry: Asymmetrical
* Nerves system: none
* Unique feeding system; tiny pores; water flow necessary
* Gas exchange by diffusssion
* Circulation: none, each cells is on its own
* Excretion: diffusion into surrounding envirmonemnt
* Reproduce by both sexual and asexual means, hermaphrodites:
Phylum Cnidarians
Common Example, Germ layers, Body cavity, Symmetry, Nerves system
- Common Example: Jellyfish, hydra, coral, sea anemone
- Germ layers: two germ layers (diplolastic)
- Body cavity: no cavity
- Symmetry: Radial symmetrical
- Nerves system: Simple net of nerves system but no centralized
hermaphrodites
meaning that each individual functions as both male and female in sexual reproduction by producing sperm and eggs
sequential hermaphroditism
They function first as one sex and then as the other
Whats the basic body plan of a Cnidarian (jellyfish, coral, anemones)
a sac with a central digestive compartment, the gastrovascular cavity
gastrovascular cavity
A single opening to this cavity functions as both mouth and anus.
Polyps
are cylindrical forms that adhere to the substrate by the aboral end of their body (the end opposite the mouth) and extend their tentacles, waiting for prey.
-many can “walk” on substrate and even detach to “swim” away
-asexual reproduction
what are hydras and sea anemones considered
Polyps
medusa
resembles a flattened, mouth-down version of the polyp. It moves freely in the water by a combination of passive drifting and contractions of its bell-shaped body.
-jellyfish
-Cnidarians sexual reproduction
body wall of a cnidarian==?
has two layers of cells, outer layer of epidermis and inner layer of gastrodermis
cnidarian mesoglea===
Sandwiched between the epidermis and gastrodermis is a gelatinous layer, the mesoglea.
cnidarian Digestion===
begins in the gastrovascular cavity and is completed inside food vacuoles in the gastrodermal cells
cnidocytes=====
cells unique to cnidarians that function in defense and prey capture
nematocysts
Specialized cnidae called nematocysts contain a stinging thread that can penetrate the body surface of the cnidarian’s prey
-Typically have tentacles that contain stinging cells called nematocysts
clade Anthozoa====
anemones and corals
clade Medusozoa
All cnidarians that produce a medusa
flatworms
phylum, germ layer, body cavity
-phylum Platyhelminthes
-lophotrochozoan phyla
-are triploblastic but they lack a body cavity (acoelomates)
-
protonephridia
in flatworms, networks of ciliated
tubules that pull fluid through ducts opening to the outside
acoelomates
lack body cavity
Planarians
-Phylum Platyhelminthes
-best-known rhabditophorans (a lineage of flat worms) are Planarians
- Planarians live in fresh water and prey on smaller animals
- Planarians have light-sensitive eyespots and centralized nerve nets
-The planarian nervous system is more complex and centralized than the nerve nets of cnidarians
- Planarians are hermaphrodites and can reproduce sexually, or asexually through fission
Two important groups of parasitic rhabditophorans are……
the trematodes
and the tapeworms
-Phylum Platyhelminthes
Trematodes
- important groups of parasitic rhabditophoran
- parasitize a wide range of hosts, and most have complex life cycles with alternating sexual and asexual stages
- Trematodes that parasitize humans spend part of their lives in snail hosts
- They produce surface proteins that mimic their host and release molecules that manipulate the host’s immune system
Tapeworms
- Phylum Platyhelminthes
Tapeworms are parasites of vertebrates - They do not have a mouth or gastrovascular cavity; instead, they
absorb nutrients directly from the host’s intestine - The scolex contains suckers and hooks for attaching to the host
- Fertilized eggs, produced by sexual reproduction, leave the host’s body in
feces
Rotifers have an alimentary canal
a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom
Rotifers reproduce by parthenogenesis
in which females produce female offspring from unfertilized eggs
Annelids
-“Segmented worms”
-are coelomates with bodies composed of a series of fused rings
-can be divided into two major clades
* Errantia
* Sedentaria
errantians
- phylum annelida
- are mobile marine predators or grazers
- Many errantians have a pair of paddle-like or ridge-like structures called parapodia (“beside feet”) on each body segment
- Each parapodium has numerous chaetae, bristles made of chitin
Sedentarians
tend to be less mobile than errantians
* Some species burrow into the substrate, while others live in protective tubes
* Tube-dwelling sedentarians often have elaborate gills or tentacles used for filter feeding
* This clade also contains the leeches and the earthworms
leeches
- phylum annelida
- Most species of leeches live in fresh water; some are marine or terrestrial
- Leeches include predators of invertebrates and parasites that suck blood
- Some parasitic leeches slit the skin of their host and secrete an anesthetic
to prevent detection - They secrete another chemical called hirudin to prevent blood from
coagulating
Earthworms
- phylum annelida
- Earthworms eat through soil, extracting nutrients as the soil moves
through the alimentary canal - Earthworms are hermaphrodites but cross-fertilize
- Some reproduce asexually by fragmentation
Four of the major classes of molluscs are……..
- Polyplacophora (chitons)
- Gastropoda (snails and slugs)
- Bivalvia (clams, oysters, and other bivalves)
- Cephalopoda (squids, octopuses, cuttlefish, and
chambered nautiluses)
-Molluscs are soft-bodied animals, but most are protected by a calcium
carbonate shell
Molluscs three main parts
- Muscular foot
- Visceral mass
- Mantle
- Many molluscs also have a water-filled mantle cavity and feed using a
strap like radula
What qualities make for a good gas exchange surface? (3)
- large surface area
- Thin and moist
- Highly vascularized
- Molluscs are our first animals to have specialized gas exchange surfaces
Chitons
- Phylum Mollusca
Chitons are oval-shaped marine animals encased in an armor of eight dorsal plates - They use their foot like a suction cup to grip rock, and their radula to scrape algae off the rock surface
gastropods
- Phylum Mollusca (snails)
About three-quarters of all living species of molluscs are gastropods - Most are marine, but there are many freshwater and terrestrial species
- Gastropods move slowly by a rippling motion of the foot or by cilia
- Most gastropods have a single, spiraled shell that functions in protection from injury, dehydration, and predation
- Most are herbivores, but some species use modified radula to feed on prey
Bivalves
-Phylum Mollusca
Bivalves are aquatic and include many species of clams, oysters, mussels, and
scallops
* They have a shell divided into two halves drawn together by adductor muscles
* Some bivalves have eyes and sensory tentacles along the edge of their mantle
Cephalopods
- Phylum Mollusca
- Cephalopods are active marine predators with beak-like jaws surrounded by tentacles (squid, octocpus, etc.)
- They are able to immobilize prey with a poison present in their saliva
- The foot is modified into a muscular excurrent siphon and part of the tentacles
- The shell is reduced and internal or missing in most species, except the chambered nautiluses
-Cephalopods have a closed circulatory system, well-developed sense organs, and a complex brain
invertebrate Importance
- 95-99% of all species
- Pollination
- Recycling
- Food in many cultures
- Food webs
- Maintenance of ecological communities
*
arthropod
- The arthropod body plan consists of a segmented body, hard exoskeleton, and jointed appendages
- This body plan dates to the Cambrian explosion (535–525 million years ago)
- Early arthropods show little variation from segment to segment
- open circulatory system
arthropod general characteristics (5)
- These modified appendages (limbs) are jointed and come in pairs
- The body of an arthropod is completely covered by the cuticle, an exoskeleton made of layers of protein and the polysaccharide chitin
- When an arthropod grows, it molts its exoskeleton
- Arthropods have eyes, olfactory receptors, and antennae that function in touch and smell
- Arthropods have an open circulatory system in which hemolymph is circulated into the spaces surrounding the tissues and organs
- A variety of organs specialized for gas exchange have evolved in arthropods
arthropods exoskeleton advantages
-helped be among the first to colonize land
- relatively impermeable to water to prevent desiccation
- Its strength provided support without reliance on the buoyancy of water
the three major arthropod lineages
- Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders)
- Myriapods (centipedes and millipedes)
- Pancrustaceans (lobsters and other crustaceans, as well as insects and their relatives)
Chelicerates
- arthropod lineage
- Chelicerates, clade Chelicerata, are named for clawlike feeding appendages called chelicerae
- The earliest chelicerates were eurypterids (water scorpions)
- Most marine chelicerates (including eurypterids) are extinct, but some species survive today, including horseshoe crabs
Most modern chelicerates are…. (4)
arachnids, which include spiders,
scorpions, ticks, and mites
Arachnids have six pairs of appendages:
the chelicerae; the pedipalps, and four pairs of walking legs
Gas exchange in spiders occurs in respiratory organs called….
book lungs
The clade Myriapoda includes
- arthropod lineage
millipedes and centipedes
-All living myriapods are terrestrial - They have a pair of antennae and three pairs of appendages modified as mouthparts
Millipedes vs Centipedes
-Millipedes eat decaying leaves and plant matter
* Millipedes have many legs, with two pairs per trunk segment
-Centipedes are carnivores
* Centipedes have one pair of legs per
trunk segment
* Poison claws on the foremost trunk
segment paralyze prey and aid in defense
Isopods
Isopods are one of the largest groups of crustaceans and include pill bugs, a well-known group of terrestrial isopods
Decapods
Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp
Planktonic crustaceans
Planktonic crustaceans include many species of copepods, which are
among the most numerous of all animals
Barnacles
Barnacles are a group of mostly sessile crustaceans
* They have a cuticle that is hardened into a calcium carbonate shell
Crustacean groups (4)
Isopods, Decapods, Planktonic crustaceans, Barnacles
Hexapoda
is an enormous clade including insects and their relatives
-Insects evolved flight without sacrificing a pair of walking legs because
wings are an extension of the cuticle
metamorphosis
Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar
-The larval stage looks entirely different from the adult stage
incomplete metamorphosis in insects
the young, called nymphs, resemble adults but
are smaller and go through a series of molts until they reach full size
* After the final molt, the wings develop and the insect becomes sexually mature
insect Fertilization
Fertilization is generally internal
* In some species copulation occurs; in others, the male deposits a sperm
packet that the female picks up
Eggs are generally laid on a food source
echinoderms
-include sea stars and sea urchins
-echinoderms are slow-moving or sessile
marine animals
* A thin epidermis covers an endoskeleton of hard calcareous plates
* Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion and feeding
* Males and females are usually separate, and sexual reproduction is external
echinoderms appearance
Most adult echinoderms appear to have radial symmetry with
multiples of five
* Their symmetry is not truly radial; the opening of the water
vascular system is not central
* Echinoderm larvae have bilateral symmetry
-include sea stars and sea urchins
sea stars
-in the clade Asteroidea
Sea stars have multiple arms radiating from a central disk
* The undersurface of each arm bears tube feet, which grip a
substrate with adhesive chemicals
* Sea stars feed on bivalves by prying them open with their tube
feet, everting their stomach, and digesting their prey externally
with digestive enzymes
* Sea stars can regrow lost arms
Living echinoderms are divided into five clades
- Asteroidea (sea stars and sea daisies)
- Ophiuroidea (brittle stars)
- Echinoidea (sea urchins and sand dollars)
- Crinoidea (sea lilies and feather stars)
- Holothuroidea (sea cucumbers)
Sea daisies
are a group of armless species in the clade Asteroidea; only
three species are known
* Sea daisies live on submerged wood and absorb nutrients through a membrane that surrounds their body
Ophiuroidea
Brittle stars have a distinct central disk and long, flexible arms that they
use for movement
* Some species are suspension feeders, while others are predators or scavengers
Echinoidea
- Sea urchins and sand dollars have no arms but have five rows of tube feet
- Sea urchins also use their spines for locomotion and protection
- Sea urchins feed on seaweed using a jaw-like structure on their underside
- Sea urchins are roughly symmetrical; sand dollars are flat disks
Crinoidea
- (sea lilies and Feather stars)
- Sea lilies live attached to the substrate by a stalk
- Feather stars can crawl using long, flexible arms
- Both use their arms in suspension feeding
- Crinoidea have changed little over the course of evolution
Holothuroidea
Sea cucumbers lack spines, have a very reduced endoskeleton, and do not look much like other echinoderms
* Sea cucumbers have five rows of tube feet; some of these are developed as feeding tentacles
Phylum Chordata
Phylum Chordata consists of two basal groups of invertebrates as well as vertebrates
* Chordates are bilaterally symmetrical coelomates with segmented bodies
* Chordates did not evolve from echinoderms, but have evolved separately from them for at least 500 million years
Phylum Cnidarians
example, germ layers, body cavity, symmetry, nervous system
- Common Example: Jellyfish, hydra, coral, sea anemone
- Germ layers: two germ layers (diplolastic)
- Body cavity: no cavity
- Symmetry: Radial symmetrical
- Nerves system: Simple net of nerves system but no centralized
Importance of invertebrates (6)
- 95-99% of all species
- Pollination
- Recycling
- Food in many cultures
- Food webs
- Maintenance of ecological communities
- ,
The bilaterians are divided into three clades:
Deuterostomia, Ecdysozoa,
and Lophotrochozoa
Ecdysozoa
Ecdysozoa secrete external skeletons
* As they grow, they shed their exoskeletons through a process called ecdysis
