Amphibians, Birds, Gastropods, Echinoderms, Plants: Adaptations
Amphibians
Amphibians have four limbs, moist, thin skin without coatings. Adults may or may not have tails; Urodeles have tails. They are poikilotherms. Adults breathe through lungs and skin, and larvae breathe through gills and are herbivores. They are oviparous with external fertilization and are the only vertebrates that undergo metamorphosis.
Birds
Birds have a streamlined body, four limbs, a body covered with feathers, hollow bones, and a horny beak. They are homeothermic, breathe through lungs connected to air sacs, and are oviparous.
Gastropods, Bivalves, and Cephalopods
Gastropods
(Pie in the head) have a well-developed head with four tentacles. They use their foot for locomotion. They have a small mouth with a radula for feeding. Nearly all possess a coiled spiral shell that protects the visceral mass. They are mostly herbivores, but some are carnivores.
Bivalves
(Two valves/shells) are articulated, and their valves are closed by powerful muscles. Their foot is small and shaped like an ax for digging. They filter water for food and breathe through gills.
Cephalopods
All are marine. They possess a well-developed head and eyes. Their mouth is surrounded by tentacles. They have no shell, breathe through gills, and are carnivores.
Echinoderms
They have radial symmetry, a rounded, cylindrical, or starry shape, an internal skeleton (endoskeleton), and a poorly differentiated head. Echinoderms move using a unique ambulacral system, a system of internal tubes filled with water, forming ambulacral feet ending in suckers. They breathe through the skin, and some have gills. They are carnivores. Some are hermaphrodites. Fertilization is external, and some have great power of regeneration.
Plant Adaptations
- Many deciduous trees lose their leaves in autumn or winter to survive.
- Some plants have large, pointed leaves to facilitate water elimination.
- Plants like the olive tree have leaves with tiny, hard hairs to prevent water loss.
- Plants in dry places store water in stems and leaves and may have thorns to prevent water loss and for defense.
- Some plants have impermeable structures, and their roots and stems are atrophied.
Pollination
Pollination is the transport of pollen grains from the anther of one flower to the stigma of another. Pollination can be done by:
- Wind
- Water
- Animals (including humans)
Fertilization and Seed/Fruit Formation
When a pollen grain reaches the stigma, it develops a pollen tube that extends from the stigma to the ovule in the ovary, where fertilization occurs. The ovule becomes the seed, containing the germ of the future plant and its food reserves. The ovary begins to grow to form the fruit, whose function is to protect and facilitate seed dispersal. The walls of the ovary form the fruit.
Seed Dispersal and Germination
Seed dispersal prevents plants from growing too close together and competing for space, nutrients, and light.
Pollination, fertilization, fruit formation, seed dispersal, and germination are all vital processes for plant reproduction.