Sponges, Cnidarians, Comb Jellies, and Marine Worms.
-
Upload
easter-walton -
Category
Documents
-
view
218 -
download
1
Transcript of Sponges, Cnidarians, Comb Jellies, and Marine Worms.
Sponges, Cnidarians, Comb Jellies, and
Marine Worms
What are Animals?• Multicellular
• Eukaryotic (lack cell walls)
• Cannot produce their own food (heterotrophs)
• Can move (exception: adult sponges)
• Vertebrates: have a backbone (vertebral column)
• Invertebrates: do not have a backbone (no vertebral column)– Majority of marine animals
Sponges (Phylum Porifera)
• Simple
• Asymmetric
• Sessile (cannot move)
Structure and Function• Full of tiny holes/pores
called ostia– Water circulation
(nutrients and oxygen)– Carries away wastes
• Lack tissues and organs
• Size is limited by ability to circulate water through its body
• 3 possible body plans
– Asconoid (simplest)-tubular and small
– Syconoid (body-wall folding)-internal pockets
– Leuconoid (highest degree of folding)
• Nutrition and digestion:
– Suspension feeders (filter feeders) Get food from water
• Reproduction– Sexual
• Hermaphrodites – Asexual
• Budding pinching off to form new organism
• Fragmentation pieces form new organism
• Ecological roles– Can produce chemicals that can kill coral or
inhibit growth– Can provide camouflage and protection for
animals– Can produce chemicals that prevent organisms
from settling on their surface or to deter grazing– Hosts to other organisms– Recycles calcium to seawater
Cnidarians (Phylum Coelenterata)
• Ex: jellyfish, hydra, coral, and sea anemones
• Radial symmetry
Structure and Function:•2 different body plans
– Polyp: benthic form• Cylindrical body with an
opening a 1 end (mouth)• Surrounded by tentacles
– Medusa: free-floating stage– Gelatinous material between
layers of body called mesoglea
• Stinging cells (cnidocytes)
–Common on tentacles and outer body wall
–Can also release toxins
• Nutrition and digestion– Digests prey in
gastrovascular cavity
– Filter-feeders– Can be
carnivores• Paralyze prey
with toxins
• Reproduction– Asexual polyp stage– Sexual medusa stage
• Ecological relationships
– Predators that feed on a variety of prey
– Provide habitats for organisms (ex: corals)
– Host symbionts that aid in nutrition and help them grow
Ctenophores (Comb Jellies)• Structure and Function:
– Transparent bodies– Lack stinging cells– Planktonic– Eight rows of comb plates
used for locomotion• Made of large cilia
– Weak swimmers– Found mostly in surface
water– Radial symmetry– Luminescent at night
• Nutrition and Digestion
– Carnivorous
• Reproduction
– Hermaphrodites
– Shed eggs and sperm directly into the water column
– Few species can brood eggs in their bodies
Marine Worms• Most are benthic
Structure:
• Elongated bodies
• Lack external hard covering
• Gain support for body from fluid in body compartments– Hydrostatic skeleton
Flatworms• Flattened bodies
Structure:
• Head and posterior end
• Free-living or parasitic
• Bilateral symmetry
Ex: flukes and tapeworms
• Nutrition and digestion:– Chemical-detecting
organs called chemoreceptors
– Carnivorous– Can subdue prey by
entangling it in mucus and suffocating it
– Can stab prey– Digestion in
gastrovascular cavity
• Reproduction:– Asexually
regeneration– Sexually
• Hermaphrodites• Can fertilize each
other• Internal fertilization• No larval stage
Nematodes• Roundworms
– 12,000 species• Structure: Round, slender body
– Elongated– Tapered at both ends
• Nutrition/Digestion: – Scavengers, parasites– Carnivorous, free-living
• Reproduction: – Most are hermaphroditic– Some can have separate sexes
Annelids• SegmentedStructure and Function:• Body wall has muscle• Skin has setae (small bristles used for
locomotion, digging, anchorage, and protection)
• Feeding and digestion:– Can have jaws or
teeth– Active predators– Chemoreceptors
monitor water currents
– Filter-feeders
• Reproduction– Asexual
• Budding• Regeneration• Fragmentation
– Sexual• Separate sexes• Gametes shed into body
cavity where they mature
• Ecological roles:
– Burrowing aids in nutrient cycling
– Burrows provide habitats for other species
– Feed on microorganisms and detritus
Examples of Annelids
polychaetes echiurans pogonophorans