intro to invertebrates Flashcards
animals that lack a backbone
invertebrates
-informally known as sponges
-are filter feeders
-lack true tissues and organs
-consist of a gelatinous noncellular mesohyl layer between two cell layers
Porifera
capturing food particles suspended in the water that passes through their body
filter feeders
Water is drawn through pores into a cavity called the _______ and out through an opening called the _______
spongocoel, osculum
flagellated collar cells, generate a water current through the sponge and ingest suspended food
choanocytes
are found in the mesohyl and play
roles in digestion and structure
amoebocytes
Sponges consist of a gelatinous noncellular ______ layer between two cell layers
mesohyl
-have diversified into a wide range of both sessile and motile forms including jellies, corals, and hydras
-exhibit a relatively simple diploblastic, radial body plan
-are carnivores that use tentacles to capture prey
-2 major clades: Medusozoa, Antozoa
cnidaria
basic body plan of a cnidarian is a sac with a
central digestive compartment
gastrovascular cavity
adheres to the substrate by the aboral end of its body
polyp
has a bell-shaped body with its mouth on the underside
medusa
tentacles are armed with this, which are unique cells that function in defense and capture of prey
cnidocytes
are specialized organelles within
cnidocytes that eject a stinging thread
nematocysts
-include all cnidarians that produce a medusa; jellies, box jellies, hydrozoans
- predominant stage in the life cycle
of most scyphozoans and cubozoans
medusozoans
-includes the corals and sea anemones
-occur only as polyps
anthozoans
external skeleton
exoskeleton
-was identified by molecular data
-includes flatworms, rotifers, ectoprocts, molluscs, annelids
lophotrochozoa
-live in marine, freshwater, and damp terrestrial habitats
-undergo triploblastic development, they are acoelomates
-dorsoventrally flattened shape maximizes surface area for gas exchange
-divided into two lineages: catenulida, rhabditophora
flatworms
-best-known rhabditophorans
- live in fresh water and prey on smaller animals
-have light-sensitive eyespots and centralized nerve nets - Their nervous system is more complex and centralized
than the nerve nets of cnidarians
-are hermaphrodites and can reproduce sexually, or
asexually through fission
planarians (free-living flatworm)
or “chain worms,” reproduce asexually by
budding
catenulida
more diverse and include both free-
living and parasitic species
rhabditophora
-parasitize a wide range of hosts, and most have complex life cycles with alternating sexual and asexual stages
- hat 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
trematodes (parasitic flatworm)
-are parasites of vertebrates and lack a
digestive system
-absorb nutrients from the host’s intestine - The scolex contains suckers and hooks for attaching to the host
- Proglottids are units that contain sex organs and form a
ribbon behind the scolex
- Fertilized eggs, produced by sexual reproduction, leave
the host’s body in feces
tapeworms (parasitic flatworm)
-are tiny animals that inhabit fresh water, the ocean, and damp soil
-are smaller than many protists but are truly multicellular and have specialized organ systems
-have an alimentary canal
-can reproduce by parthenogenesis
rotifers
a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom
alimentary canal
where females produce offspring from unfertilized eggs.
parthenogenesis
-have a lophophore, a crown of ciliated tentacles around their mouth
-have a true coelom
-include two phyla: Ectoprocta and
Brachiopoda
lophophorates
- (also called bryozoans) are sessile
colonial animals that can superficially resemble plants or corals
-A hard exoskeleton encases the colony, and some species are reef builders
ectoprocts
-superficially resemble clams and other
hinge-shelled molluscs, but the two halves of the shell are dorsal and ventral rather than lateral as in clams
-are marine and most attach to the seafloor by a stalk
brachiopods
-includes snails and slugs, oysters and clams, and octopuses and squids
-are marine, though some inhabit fresh water and some snails and slugs are terrestrial
-are soft-bodied animals, but most are protected by a hard shell
molluscs
Many molluscs also have a water-filled _____ ____ and feed using a rasplike ______
mantle cavity, radula
-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
chitons
-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
-The mantle cavity contains gills that are used for feeding as well as gas exchange
bivalves
-About three-quarters of all living species of molluscs
-are marine, but many are freshwater and terrestrial species
-move slowly by a rippling motion of the foot or by cilia
-Most 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
gastropods
- are carnivores with beak-like jaws surrounded by tentacles of their modified foot
-They are able to immobilize prey with a poison present in their saliva
-have a closed circulatory system, well-
developed sense organs, and a complex brain
cephalopods
shelled cephalods
ammonites
-are coelomates with bodies composed of a series of fused rings
-divided into two major clades; errantia, sedantaria
annelids
-mobile, marine organisms
-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
-Parapodia are not unique to this clade
errantians
-tend to be less mobile than errantians
-Some species burrow into the substrate, while others live in protective tubes
-Tube-dwelling ___ often have elaborate gills or tentacles used for filter feeding
-This clade also contains the leeches and the
earthworms
sedentarians
-live in fresh water; some are marine or terrestrial
-include predators of invertebrates, and parasites that suck blood
-secrete a chemical called hirudin to prevent blood from coagulating
leeches
-eat through soil, extracting nutrients as the soil moves through the alimentary canal
-are hermaphrodites but cross-fertilize
-Some reproduce asexually by fragmentation
earthworms
-are found in nearly all habitats of the biosphere.
-most successful animal phylum.
-body plan consists of a segmented
body, hard exoskeleton, and jointed appendages
arthropods
ecdysozoan are covered by a tough coat called a
cuticle
-roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals
-They have an alimentary canal, but lack a circulatory system
-Body wall muscles are all longitudinal, and their contraction produces a thrashing motion
nematodes
(sea spiders, horseshoe crabs, scorpions,
ticks, mites, and spiders)
chelicerates
(centipedes and millipedes)
myriapods
Arthropods have an _______ in which hemolymph is circulated into the spaces surrounding the tissues and organs (hemocoel)
open circulatory system
(lobsters and other crustaceans, as well
as insects and their relatives)
pancrustaceans
-named for clawlike feeding appendages called chelicerae
-have an anterior cephalothorax and a posterior abdomen
-have six pairs of appendages: the
chelicerae (fangs), the pedipalps (various roles, including reproduction), and four pairs of walking legs
-Most modern are arachnids, which include spiders, scorpions, ticks, and mites
chelicerates
gas exchange in spiders occurs in respiratory organs called
book lungs
-includes millipedes and centipedes
-terrestrial
-They have a pair of antennae and three pairs of appendages modified as mouthparts
myriapods
-eat decaying leaves and plant matter
-have many legs, with two pairs per trunk segment
millipedes
-terrestrial insects are more closely related to crustaceans than myriapods
-are more closely related to insects than other crustaceans (hence they are paraphyletic)
-insects and crustaceans form this clade
pancrustaceans
-are carnivores
-have one pair of legs per trunk segment
-Poison claws on the foremost trunk segment paralyze prey and aid in defense
centipedes
-live in marine and freshwater environments; Include crabs, lobsters, shrimp, barnacles, etc.
-have highly specialized appendages (up to 19 pairs!)
-Small crustaceans exchange gases through the cuticle; larger crustaceans have gills
have separate males and females
-Isopods and amhipods include terrestrial, freshwater, and marine species
crustaceans
-diversified several times following the
evolution of flight, adaptation to feeding on gymnosperms, and the expansion of angiosperms (359-251 mya)
-declined during the Cretaceous extinction, but has been increasing in the 65 million years since
-undergo metamorphosis during their development
insects
the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size
incomplete metamorphosis
-are a group of armless species in the clade
Asteroidea; only three species are known
-live on submerged wood and absorb
nutrients through a membrane that surrounds their body
asteroidea: sea daisies
have larval stages known by such names as maggot, grub, or caterpillar
complete metamorphosis
-share developmental characteristics
-Radial cleavage
-Formation of the anus from the blastopore
-defined primarily by DNA similarities
deuterostomes
- slow-moving or sessile marine animals
-A thin epidermis covers an endoskeleton of hard calcareous plates
-Males and females are usually separate, and sexual reproduction is external
-have a unique water vascular system,
a network of hydraulic canals branching into tube feet that function in locomotion and feeding, pentaradial symmetry
-adults have radial symmetry w pentaradial; larvae have bilateral symmetry
echinoderms
-have multiple arms radiating from a central disk
-feed on bivalves by prying them open with their tube feet, everting their stomach, and digesting their prey externally with digestive enzymes
-can regrow lost arms
asteroidea: sea stars
Echinoderms have a unique ________, a network of hydraulic canals branching into _______ that function in locomotion and feeding, pentaradial symmetry
water vascular system, tube feet
-have a distinct central disk and long, flexible arms, which they use for movement
-Some species are suspension feeders, while others are predators or scavengers
ophiuroidea: brittle stars
-consists of two basal groups of invertebrates as well as vertebrates
-are bilaterally symmetrical coelomates with segmented bodies
-did not evolve from echinoderms, but evolved separately from them for at least 500 million years
chordates
-live attached to the substrate by a stalk
-Feather stars can crawl using long, flexible arms
-Both are suspension feeders
-Crinoidea have changed little over the course of evolution
crinoidea: sea lilies and feather stars
-have no arms but have five rows of tube feet
-Their spines are used for locomotion and protection
-feed on seaweed using a jaw-like
structure on their underside
echinoidea: sea urchins and sand dollars
-lack spines, have a very reduced endoskeleton, and do not look much like other echinoderms
- have five rows of tube feet; some of these are developed as feeding tentacles
holothuroidea: sea cucumbers
