ANIMALES INVERTEBRADOS para niños - Artrópodos, moluscos, gusanos, celentéreos y equinodermos

Introduction to Invertebrates

Overview of Animal Classification

• Animals are divided into two main groups: vertebrates (with internal skeletons) and invertebrates (without bones) .

• Invertebrates are classified into six major groups: sponges, jellyfish and corals, worms, mollusks, echinoderms, and arthropods .

Characteristics of Sponges

• Sponges are aquatic animals with a sack-like shape filled with pores; they are commonly used for personal hygiene in showers .

Jellyfish and Corals

• Jellyfish have gelatinous bodies with tentacles that can sting; they can be problematic when washed ashore due to their venomous stings .

• Corals are tiny marine animals that produce calcareous residues forming beautiful structures in the ocean .

Worms and Mollusks

Worm Characteristics

• Worms are soft-bodied invertebrates that move by dragging their bodies along surfaces; they can be either aquatic or terrestrial. Some may pose health risks .

Mollusk Features

• Mollusks have soft bodies without legs; some protect themselves with shells (e.g., snails and mussels), while others do not have shells (e.g., slugs and octopuses) .

Echinoderms and Arthropods

Echinoderm Traits

• Echinoderms live exclusively in marine environments; their bodies feature calcareous plates forming a shell. Examples include sea urchins and starfish .

Arthropod Diversity

• Arthropods make up the majority of animal species on Earth, characterized by an external skeleton called a cuticle. They can be classified based on the number of legs:

• Six-legged arthropods include insects like ants and flies.

• Eight-legged arthropods consist of arachnids such as spiders.

• Ten-legged arthropods encompass crustaceans like crabs.

• Myriapods have more than ten legs, exemplified by centipedes .

Vertebrate vs. Invertebrate Animals

Vertebrate Characteristics

• Vertebrates possess internal skeleton structures made of bones. Examples include elephants, birds, frogs, etc. The skeletal structure varies among different vertebrate types: mammals, birds, reptiles, fish, amphibians .

Invertebrate Groups Recap

• Invertebrates lack internal skeleton systems. Key groups include:

• Arthropods

• Mollusks

• Annelids

• Echinoderms

• Sponges

• Cnidarians .

Identifying Vertebrates and Invertebrates

Examples of Identification

• Bears are vertebrates as they possess bones.

• Slugs belong to the mollusk group as invertebrates without bones.

• Eagles qualify as vertebrates since they have an internal skeletal system.

• Bees fall under the category of invertebrates as arthropods without an internal skeleton .

Insect Characteristics

Common Features of Insects

• Insects represent a significant portion of animal life on Earth; characteristics include:

• Body divided into head, thorax, abdomen.

• Two antennae and six legs.

• Respiration through tracheae [].

Metamorphosis Process

Insect Metamorphosis and Characteristics

Understanding Insect Life Cycle

• Insects undergo a significant transformation known as metamorphosis, specifically the pupa stage, where they change from larvae to adult insects.

• Most insects possess wings, making them the only group of invertebrates capable of flight. They also have compound eyes that provide nearly perfect vision and excellent peripheral sight.

Diversity of Insects

• There is a vast variety of insects, ranging from bothersome ones like lice and mosquitoes to fascinating forms such as stick insects and leaf insects.

• Social insects like ants and bees live in organized colonies with specific roles: queen ants lay eggs, while worker ants gather food and care for larvae.

Importance of Insects in Nature

• Despite their small size, insects play crucial roles in maintaining ecological balance; they are essential for pollination alongside birds.

• Bees are highlighted for their role in pollinating flowers, which leads to the growth of new plants.

Characteristics of Arthropods

Defining Features of Arthropods

• Arthropods are invertebrate animals characterized by jointed legs. The term "arthropod" derives from Latin meaning "jointed feet."

• Common traits include segmented bodies and an external skeleton that serves as protection. Some arthropods undergo molting when their exoskeleton no longer fits due to growth.

Habitat and Diet

• Arthropods can be terrestrial or aquatic; terrestrial species breathe through tracheae while aquatic ones use gills.

• Their diets vary widely: some are herbivores (like caterpillars), others carnivores (like praying mantises), while many are omnivores (like wasps).

Reproduction and Classification

• Arthropods reproduce through internal fertilization, laying eggs that hatch into larvae undergoing metamorphosis into adults.

• They are classified into four main groups based on leg count:

• Insects (6 legs)

• Arachnids (8 legs)

• Crustaceans (10 legs)