Animalia Kingdom Characteristics
📌 Animals belong to the Eukaryotic kingdom, characterized by having a membrane-bound nucleus, and are multicellular.
🍔 Animals are heterotrophs, consuming organic matter, contrasting with autotrophs that utilize light for photosynthesis.
🏃‍♂️ Key characteristics include aerobic respiration, possessing muscle cells (myocytes), and being generally motile (though some, like corals, are sessile as adults).
⚽ Development originates from a hollow ball of cells (blastula) which eventually forms tissues and organs through processes like gastrulation, defining germ layers (ectoderm, mesoderm, endoderm).

Animal Phylogeny Overview (Giribet & Edgecombe, 2020)
🦠 The simplest animals include Porifera (sponges) and Ctenophora (comb jellies), which lack true tissues.
🧬 Parazoa is characterized by the presence of Hox genes, which determine the body plan along the head-tail axis.
🕸️ Bilateria encompasses animals with bilateral symmetry, further divided into Protostomia and Deuterostomia based on blastopore fate (mouth vs. anus formation first).

Deuterostomia Grouping
⭐ Deuterostomia branches into Ambulacralia and Chordata.
🌊 Echinodermata (sea stars, sea urchins) are a prominent group within Ambulacralia.
🐟 Chordata includes subphyla like Urochordata (tunicates) and Vertebrata (animals with a backbone, including humans).

Protostomia Grouping: Spiralia and Ecdysozoa
🌀 Spiralia includes major phyla such as Platyhelminthes (flatworms), Annelida (segmented worms like earthworms and leeches), and Mollusca (snails, clams, squid).
🛡️ Ecdysozoa are characterized by molting (shedding the exoskeleton), divided into Scalidophora and Panarthropoda.
🐛 Panarthropoda groups Tardigrada (water bears), Onychophora (velvet worms), and Arthropoda.

Arthropoda Subphyla and Characteristics
🦵 Arthropods possess jointed appendages (arthron + podos), exhibit bilateral symmetry, are triploblastic, and are protostomes.
🌱 They possess an exoskeleton made of chitin, often mineralized with calcium carbonate, and undergo molting.
🩸 Circulation is open, using hemolymph in a body cavity called the hemocoel.
🐜 The body is segmented into tagmata (e.g., cephalothorax, abdomen).

Chelicerata Subphylum Details
🕷️ Members possess chelicerae (feeding appendages).
🐴 Xiphosura (horseshoe crabs, e.g., *Tachypleus gigas*) have a sword-like tail called a telson.
🕸️ Arachnida (spiders, scorpions) typically have four pairs of legs and a body divided into two tagmata: cephalothorax (prosoma) and opisthosoma (abdomen).
🦂 Scorpions are distinguished by having a segmented abdomen (mesosoma and metasoma) ending in a venomous stinger (aculeus).

Myriapoda Subphylum Details
🌿 Myriapoda includes Chilopoda (centipedes, one pair of legs per segment, carnivorous) and Diplopoda (millipedes, two pairs of legs per segment, herbivorous).
👟 Centipedes (like the common *lipan*) are typically predatory, while millipedes (*keliing*) curl up when disturbed and are detritivores/herbivores.

Crustacea Subphylum Details
🦞 Crustaceans (e.g., shrimp, crabs) are distinguished by having antennae and antennules and typically possess five pairs of pereiopods (walking legs).
🦀 Body is usually divided into a cephalothorax and abdomen.
💧 Appendages in the abdomen are often pleopods (swimmerets) used for swimming.

Hexapoda Subphylum Details (Insects and Relatives)
🐛 Hexapods possess three body tagmata (head, thorax, abdomen) and three pairs of legs attached to the thorax.
🦗 The class Insecta is defined by having three pairs of legs and often wings attached to the thorax.
🌟 Insect mouthparts vary significantly (e.g., chewing-biting types seen in grasshoppers).
💨 Collembola (springtails) are now separate from Insecta but share the three-tagma structure; they are named for the furcula, an abdominal appendage used for jumping.

Key Points & Insights
➡️ Animalia cells are eukaryotic and multicellular, functioning as heterotrophs.
➡️ Phylogenetic grouping relies on features like the presence of Hox genes (Parazoa vs. others) and blastopore fate (Protostomia vs. Deuterostomia).
➡️ Arthropods are defined by jointed legs, a chitinous exoskeleton, open circulatory systems, and segmented bodies (tagmata).
➡️ Chelicerates (spiders, scorpions) are identified by their chelicerae, while Myriapods are split between carnivorous centipedes and herbivorous millipedes based on leg count per segment.

📸 Video summarized with SummaryTube.com on Dec 10, 2025, 05:39 UTC